Dwarf caves in all modes: neutral dwarves guard a hoard and sometimes a rune chest; the rune forge tower; imps repair towers before claiming

- 1-4 cave slots by map size, 50% each (at least one); knight treasure caves only where a mission places them
- dwarves fight intruders near the cave, never chase far, heal at home, grow with distance and the player's army, never count for victory
- rune chest: one free rune forge tower (chain bolt to three more enemies), upgradeable for gold, sold once it comes back (next mission / free play at once), unbuilt ones carry over
- new tool (key N) shown in the tower menu while a rune tower can be built or upgraded

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

DESIGN.md

@@ -55,7 +55,10 @@ An original dungeon management game (genre: dungeon building & defence) that run
 - Chosen in the **New Game dialog**: width and height separately, **64–256 tiles** in steps of 32 (remembered in the settings)
 - Content scales with the area: rock, gold veins and caves; the Hero Gate lies on the far side, the **grace period grows with the distance** to the gate
 - **One portal per 64×64 tiles**; every claimed portal brings creatures (more portals = faster arrivals, still limited by the lair)
-- Bigger maps get **guarded treasure caves** (one less than the number of portals): very rich gold veins, defended by a hero squad that stays at its post
+- **Dwarf caves** in every mode: 1 to 4 slots depending on the map size, each filled with a 50% chance (at least one cave). A hoard (1500-4000 in gold and gems, more the further from the core) inside a cave ringed by rich veins, guarded by 4-6 neutral dwarves (bronze rings). Dwarves fight whoever comes within about 7 tiles of the cave, never chase further, heal at home and never count as opponents for victory. Their level grows with the distance to the core, and every 30 s they gain levels until they match about half the player's army strength.
+- Knight treasure caves only exist where a campaign mission places them; everywhere else dwarf caves took their place.
+- 30% of the dwarf caves hold a **rune chest**: claiming it gives one free build of the **rune forge tower** (1400 HP, range 10, the rune bolt jumps on to three more enemies). It can be upgraded for gold (800 / 1200). Selling it returns the base tower once: in the campaign as a chest for the next mission, in free play at once. Unbuilt rune towers carry over to the next mission.
+- Imps repair damaged towers for free; repairs come before claiming more ground.
 - Savegames store the tiles packed (run-length encoded, base64), so even 256×256 maps stay small (~300 KB); version 1 savegames still load
 
 ## Game content

README.md

@@ -10,7 +10,7 @@ Dig out your underground realm, claim the portal to attract creatures, keep them
 - 3D isometric view with a freely rotatable and tiltable camera
 - Procedural pixel art, irregular cave walls, flickering torch light
 - CP437 text-mode style interface with the DINOBYTE bitmap font
-- Map sizes from 64×64 to 256×256 tiles (one portal per 64×64 tiles, guarded treasure caves on bigger maps)
+- Map sizes from 64×64 to 256×256 tiles (one portal per 64×64 tiles, dwarf caves with treasure and rune forge plans)
 - English and German (language files in `lang/`, easy to extend)
 
 See [DESIGN.md](DESIGN.md) for all design decisions and [CREDITS.md](CREDITS.md) for third-party assets.

lang/de.lang

@@ -624,3 +624,17 @@ hud.rival1 = Grün
 hud.rival2 = Blau
 msg.creature_freed = Ein {0} sprengt seine Ketten und schließt sich dir an!
 msg.spring_taken = Eine Manaquelle gehört dir: mehr Mana und ein höheres Maximum.
+tool.rune.label = Rune
+tool.rune.name = Runenschmiede-Turm
+tool.rune.desc = Pläne aus einer Zwergenkiste: kostenlos gebaut, ein Turm je Kiste. Riesige Reichweite, Runenblitze springen auf drei weitere Feinde über. Verkaufst du ihn, kommt der Basisturm einmal zurück, in der nächsten Mission.
+tower.rune = Runenschmiede-Turm
+cost.rune = kostenlos: noch {0} (Ausbau {1} / {2} Gold)
+hint.rune_none = Keine Runenschmiede-Pläne mehr. Nimm eine Zwergenkiste ein, um neue zu bekommen.
+msg.rune_chest = Eine Zwergenkiste! Die Pläne eines Runenschmiede-Turms gehören dir - bau ihn kostenlos im Turmmenü.
+msg.rune_next = Die Runenschmiede-Pläne sind verstaut: Der Turm kommt in der nächsten Mission zurück.
+msg.rune_back = Die Runenschmiede-Pläne sind zurück - du darfst den Turm noch einmal bauen.
+msg.dwarf_slain = Ein Zwerg fällt. +{0} Gold.
+info.dwarf = Bewacht den Schatz einer Zwergenhöhle
+info.dwarf_neutral = Neutral: kämpft gegen jeden, der zu nahe kommt, verlässt die Höhle nie.
+tile.rune_chest = Zwergische Runenkiste
+tile.rune_chest_info = Nimm sie ein: die Pläne eines Runenschmiede-Turms (einmal kostenlos bauen).

lang/en.lang

@@ -625,3 +625,17 @@ hud.rival1 = Green
 hud.rival2 = Blue
 msg.creature_freed = A {0} breaks its chains and joins you!
 msg.spring_taken = A mana spring is yours: more mana and a higher maximum.
+tool.rune.label = Rune
+tool.rune.name = Rune Forge Tower
+tool.rune.desc = Plans from a dwarven chest: built for free, one tower per chest. Huge range, rune bolts jump on to three more enemies. Sell it and the base tower comes back once, in the next mission.
+tower.rune = Rune Forge Tower
+cost.rune = free: {0} left (upgrades {1} / {2} gold)
+hint.rune_none = No rune forge plans left. Claim a dwarven chest for a new one.
+msg.rune_chest = A dwarven chest! The plans of a rune forge tower are yours - build it for free from the tower menu.
+msg.rune_next = The rune forge plans are packed away: the tower comes back in the next mission.
+msg.rune_back = The rune forge plans are back - you may build the tower once more.
+msg.dwarf_slain = A dwarf falls. +{0} gold.
+info.dwarf = Guards the hoard of a dwarf cave
+info.dwarf_neutral = Neutral: fights whoever comes close, never leaves the cave.
+tile.rune_chest = Dwarven rune chest
+tile.rune_chest_info = Claim it: the plans of a rune forge tower (one free build).

src/campaign.rs

@@ -10,7 +10,7 @@ use serde::{Deserialize, Serialize};
 // From which mission (0-based) on each tool is available (same order as ui::TOOLS):
 // dig, hand, treasury, lair, farm, training, library, sell, flag, lightning, heal, imp,
 // torture, temple, arrow tower, cannon tower, magic tower, bridge, aerie, steel
-pub const TOOL_UNLOCK: [usize; 20] = [0, 0, 0, 0, 0, 2, 5, 0, 0, 3, 5, 0, 8, 12, 3, 7, 12, 1, 8, 17];
+pub const TOOL_UNLOCK: [usize; 21] = [0, 0, 0, 0, 0, 2, 5, 0, 0, 3, 5, 0, 8, 12, 3, 7, 12, 1, 8, 17, 0];
 
 pub struct FortDef {
     pub at: (f32, f32), // centre as a fraction of the map size
@@ -79,6 +79,10 @@ fn cave(at: (f32, f32), chained: Option<(EK, u32)>, treasure: i32) -> CaveDef {
 pub struct Carry {
     pub creatures: Vec<(EK, u32, f32)>, // kind, level, experience
     pub gold: f32,
+    #[serde(default)]
+    pub rune_free: u32, // unbuilt rune forge towers from chests
+    #[serde(default)]
+    pub rune_final: u32, // unbuilt or sold rune forge towers that were already given back once
 }
 
 pub const CARRY_CREATURES: usize = 5;
@@ -499,6 +503,7 @@ pub fn start_mission(i: usize, carry: Option<&Carry>) -> Game {
         let y = ((ry * h as f32) as i32).clamp(10, h as i32 - 10);
         g.add_rival(side, x, y, diff);
     }
+    g.place_dwarf_caves(d.seed);
     let heart = d.gate || d.forts.iter().any(|f| f.heart);
     if !heart {
         g.gate_hp = 0.0;
@@ -524,6 +529,8 @@ pub fn start_mission(i: usize, carry: Option<&Carry>) -> Game {
     if let Some(c) = carry {
         joiners.extend(c.creatures.iter().copied());
         g.gold += c.gold;
+        g.rune_free += c.rune_free;
+        g.rune_final += c.rune_final;
     }
     for (k, &(kind, level, xp)) in joiners.iter().enumerate() {
         let a = k as f32 * 0.9;
@@ -543,7 +550,7 @@ pub fn carry_from(g: &Game) -> Carry {
     let mut c: Vec<&Ent> = g.ents.iter().filter(|e| e.alive && e.creature()).collect();
     let power = |e: &Ent| e.max_hp * e.atk() / st(e.kind).interval;
     c.sort_by(|a, b| power(b).partial_cmp(&power(a)).unwrap_or(std::cmp::Ordering::Equal));
-    Carry { creatures: c.iter().take(CARRY_CREATURES).map(|e| (e.kind, e.level, e.xp)).collect(), gold: (g.gold * CARRY_GOLD).floor() }
+    Carry { creatures: c.iter().take(CARRY_CREATURES).map(|e| (e.kind, e.level, e.xp)).collect(), gold: (g.gold * CARRY_GOLD).floor(), rune_free: g.rune_free, rune_final: g.rune_final + g.rune_next }
 }
 
 #[cfg(test)]

src/dwarves.rs

@@ -0,0 +1,355 @@
+// Dwarf caves: a neutral people that guards a treasure in a cave surrounded by rich veins.
+// The dwarves defend themselves but never stray far from their cave, and they never count
+// as opponents for victory. Some caves hold a chest with the plans of a rune forge tower:
+// the player may build it once for free.
+
+use crate::game::*;
+use crate::map::*;
+use serde::{Deserialize, Serialize};
+
+pub const DWARF_SIDE: u8 = 4;
+const LEASH: f32 = 7.0; // dwarves do not chase enemies further from the cave centre
+const CHEST_CHANCE: f32 = 0.3;
+
+#[derive(Clone, Debug, Serialize, Deserialize)]
+pub struct DwarfCave {
+    pub at: (i32, i32), // centre
+    pub base: u32,      // base level of its dwarves (grows with the distance to the player's core)
+}
+
+impl Game {
+    // 1 to 4 cave slots depending on the map size, each filled with a 50% chance (at least one)
+    pub fn place_dwarf_caves(&mut self, seed: u32) {
+        let mut rng = Rng(seed.wrapping_mul(0x9e37_79b9) ^ 0x5bd1_e995 | 1);
+        for _ in 0..8 {
+            rng.next();
+        }
+        let area = (mw() * mh()) as f32 / 4096.0;
+        let slots = (area.sqrt().ceil() as usize).clamp(1, 4);
+        let mut n = (0..slots).filter(|_| rng.f() < 0.5).count();
+        if n == 0 {
+            n = 1;
+        }
+        for _ in 0..n {
+            if let Some(at) = self.dwarf_spot(&mut rng) {
+                self.carve_dwarf_cave(at, &mut rng);
+            }
+        }
+    }
+
+    // a spot far from everything else whose surroundings are untouched neutral rock and earth
+    fn dwarf_spot(&self, rng: &mut Rng) -> Option<(i32, i32)> {
+        let (w, h) = (mw() as i32, mh() as i32);
+        let (cx, cy) = (self.map.core.0 + 1, self.map.core.1 + 1);
+        let mut others: Vec<(i32, i32)> = vec![(cx, cy), (self.map.gate.0 + 1, self.map.gate.1 + 1)];
+        others.extend(self.map.portals.iter().map(|&(x, y)| (x + 1, y + 1)));
+        others.extend(self.map.treasures.iter().copied());
+        others.extend(self.rivals.iter().map(|r| (r.core.0 + 1, r.core.1 + 1)));
+        others.extend(self.dwarf_caves.iter().map(|c| c.at));
+        let mut best = None;
+        let mut bd = -1;
+        for _ in 0..200 {
+            let p = (rng.range(9, w - 10), rng.range(9, h - 10));
+            if (p.0 - cx).pow(2) + (p.1 - cy).pow(2) < 20 * 20 {
+                continue;
+            }
+            let clear = (p.1 - 6..=p.1 + 6).all(|y| {
+                (p.0 - 6..=p.0 + 6).all(|x| {
+                    let t = &self.map.t[idx(x, y)];
+                    t.owner == Owner::None && !t.liquid() && !matches!(t.kind, Kind::Core | Kind::Portal | Kind::Gate | Kind::Tower | Kind::Shard | Kind::Bridge | Kind::LavaBridge | Kind::Treasury | Kind::ManaSpring | Kind::RuneChest)
+                })
+            });
+            if !clear {
+                continue;
+            }
+            let d = others.iter().map(|q| (p.0 - q.0).pow(2) + (p.1 - q.1).pow(2)).min().unwrap_or(i32::MAX);
+            if d < 14 * 14 {
+                continue;
+            }
+            // not hidden among the knights: keep off fortress ground and units
+            if self.ents.iter().any(|e| e.alive && (e.x - p.0 as f32).abs() < 8.0 && (e.y - p.1 as f32).abs() < 8.0) {
+                continue;
+            }
+            if d > bd {
+                bd = d;
+                best = Some(p);
+            }
+        }
+        best
+    }
+
+    fn carve_dwarf_cave(&mut self, (cx, cy): (i32, i32), rng: &mut Rng) {
+        let (px, py) = (self.map.core.0 + 1, self.map.core.1 + 1);
+        let dist = (((cx - px).pow(2) + (cy - py).pow(2)) as f32).sqrt();
+        // rich veins around the cave, with gems
+        for y in cy - 5..=cy + 5 {
+            for x in cx - 5..=cx + 5 {
+                let d = (((x - cx).pow(2) + (y - cy).pow(2)) as f32).sqrt();
+                let t = &mut self.map.t[idx(x, y)];
+                t.marked = false;
+                t.reinforced = false;
+                t.hp = 6.0;
+                if (x - cx).abs() <= 2 && (y - cy).abs() <= 2 {
+                    t.kind = Kind::Floor;
+                    t.gold = 0;
+                } else if d <= 5.2 && rng.f() < 0.7 {
+                    let r = rng.f();
+                    let (k, g) = if r < 0.08 { (Kind::Diamond, rng.range(1200, 1800)) } else if r < 0.28 { (Kind::Ruby, rng.range(800, 1200)) } else if r < 0.45 { (Kind::Silver, rng.range(500, 800)) } else { (Kind::Gold, rng.range(800, 1400)) };
+                    t.kind = k;
+                    t.gold = g;
+                } else {
+                    t.kind = Kind::Earth;
+                    t.gold = 0;
+                }
+            }
+        }
+        // the hoard: treasury piles in the corners and along the walls, more the further away
+        let hoard = (1500.0 + dist * 20.0).min(4000.0) as i32;
+        let spots = [(-2, -2), (2, -2), (-2, 2), (2, 2), (0, -2), (0, 2), (-2, 0), (2, 0)];
+        let piles = ((hoard + TREASURY_TILE as i32 - 1) / TREASURY_TILE as i32).clamp(1, spots.len() as i32) as usize;
+        for (k, &(dx, dy)) in spots.iter().take(piles).enumerate() {
+            let t = &mut self.map.t[idx(cx + dx, cy + dy)];
+            t.kind = Kind::Treasury;
+            t.gold = (hoard - k as i32 * TREASURY_TILE as i32).clamp(0, TREASURY_TILE as i32);
+            let r = rng.f();
+            t.res = if r < 0.12 { 3 } else if r < 0.35 { 2 } else if r < 0.55 { 1 } else { 0 };
+        }
+        if rng.f() < CHEST_CHANCE {
+            self.map.t[idx(cx, cy)].kind = Kind::RuneChest;
+        }
+        let base = (2 + (dist / 30.0) as u32).min(7);
+        let count = 4 + (dist > 60.0) as usize + (dist > 100.0) as usize;
+        for k in 0..count {
+            let a = k as f32 / count as f32 * std::f32::consts::TAU;
+            let id = self.spawn(EK::Dwarf, false, cx as f32 + 0.5 + a.cos() * 1.2, cy as f32 + 0.5 + a.sin() * 1.2, base);
+            if let Some(e) = self.ents.iter_mut().find(|e| e.id == id) {
+                e.side = DWARF_SIDE;
+                e.home = Some((cx as f32 + 0.5, cy as f32 + 0.5));
+                e.happy = 1.0;
+            }
+        }
+        self.dwarf_caves.push(DwarfCave { at: (cx, cy), base });
+    }
+
+    // Every 30 s the dwarves of a cave grow stronger until they match about half the player's
+    // army (or their base level): one of the weakest idle dwarves gains a level.
+    pub fn update_dwarves(&mut self, dt: f32) {
+        self.dwarf_t -= dt;
+        if self.dwarf_t > 0.0 || self.dwarf_caves.is_empty() {
+            return;
+        }
+        self.dwarf_t = 30.0;
+        let army = self.army_value() * 0.5;
+        for c in 0..self.dwarf_caves.len() {
+            let home = (self.dwarf_caves[c].at.0 as f32 + 0.5, self.dwarf_caves[c].at.1 as f32 + 0.5);
+            let mine: Vec<usize> = (0..self.ents.len()).filter(|&j| {
+                let e = &self.ents[j];
+                e.alive && e.dwarf() && e.home == Some(home)
+            }).collect();
+            if mine.is_empty() {
+                continue;
+            }
+            let list: Vec<(EK, u32)> = mine.iter().map(|&j| (self.ents[j].kind, self.ents[j].level)).collect();
+            if Game::squad_value(&list) >= army {
+                continue;
+            }
+            if let Some(&j) = mine.iter().filter(|&&j| self.ents[j].level < 10 && !matches!(self.ents[j].job, Job::Attack(_))).min_by_key(|&&j| self.ents[j].level) {
+                let e = &mut self.ents[j];
+                e.level += 1;
+                let old = e.max_hp;
+                e.max_hp = st(e.kind).hp * (1.0 + 0.15 * (e.level - 1) as f32);
+                e.hp += e.max_hp - old;
+            }
+        }
+    }
+
+    // a dwarf: fights what comes close to the cave, otherwise potters about at home and heals
+    pub fn dwarf_ai(&mut self, e: &mut Ent, dt: f32) {
+        let (hx, hy) = e.home.unwrap_or((e.x, e.y));
+        let from_home = |x: f32, y: f32| ((x - hx).powi(2) + (y - hy).powi(2)).sqrt();
+        if e.think <= 0.0 {
+            e.think = 0.4;
+            if !matches!(e.job, Job::Attack(_)) {
+                if let Some(id) = self.nearest_enemy(e, 6.5) {
+                    if let Some(j) = self.find(id) {
+                        if from_home(self.ents[j].x, self.ents[j].y) < LEASH {
+                            e.job = Job::Attack(id);
+                            e.path.clear();
+                            e.repath = 0.0;
+                        }
+                    }
+                }
+            }
+        }
+        if let Job::Attack(id) = e.job {
+            let near = self.find(id).map_or(false, |j| from_home(self.ents[j].x, self.ents[j].y) < LEASH + 1.0);
+            if near && from_home(e.x, e.y) < LEASH + 1.0 && self.attack_job(e, id, dt) {
+                return;
+            }
+            e.job = Job::None;
+            e.path.clear();
+            e.repath = 0.0;
+        }
+        e.hp = (e.hp + e.max_hp * 0.01 * dt).min(e.max_hp);
+        if e.path.is_empty() && e.repath <= 0.0 {
+            e.repath = 3.0 + self.rng.f() * 4.0;
+            let (tx, ty) = if from_home(e.x, e.y) > 3.0 { (hx, hy) } else { (hx + self.rng.f() * 4.0 - 2.0, hy + self.rng.f() * 4.0 - 2.0) };
+            if self.map.walk(tx as i32, ty as i32) {
+                if let Some(p) = self.map.path_to(e.tile(), idx(tx as i32, ty as i32)) {
+                    e.path = p;
+                }
+            }
+        }
+        self.step_path(e, dt);
+    }
+
+    // rune forge towers that can be built now
+    pub fn rune_available(&self) -> u32 {
+        self.rune_free + self.rune_final
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    fn dwarves(g: &Game) -> usize {
+        g.ents.iter().filter(|e| e.alive && e.dwarf()).count()
+    }
+
+    #[test]
+    fn caves_by_map_size() {
+        for seed in 1..=10u32 {
+            for &(w, h, max) in &[(64usize, 64usize, 1usize), (128, 128, 2), (256, 256, 4)] {
+                let g = Game::new_free(seed, w, h, 1);
+                let n = g.dwarf_caves.len();
+                assert!(n >= 1 && n <= max, "seed {} {}x{}: {} caves", seed, w, h, n);
+                assert!(g.map.treasures.is_empty(), "knight caves replaced");
+                assert!(dwarves(&g) >= 4 * n);
+                for c in &g.dwarf_caves {
+                    let t = &g.map.t[idx(c.at.0, c.at.1)];
+                    assert!(matches!(t.kind, Kind::Floor | Kind::RuneChest), "cave centre {:?}", t.kind);
+                }
+            }
+        }
+    }
+
+    #[test]
+    fn dwarves_are_no_opponents_and_stay_home() {
+        let mut g = (1..100u32).map(|s| Game::new_free(s, 64, 64, 0)).find(|g| g.rivals.len() == 1 && !g.gate_on).unwrap();
+        g.eliminate_rival(0);
+        for _ in 0..40 {
+            g.update(0.05);
+        }
+        assert_eq!(g.state, 1, "dwarves alive, but the game is won");
+        assert!(dwarves(&g) > 0);
+    }
+
+    #[test]
+    fn dwarves_fight_intruders_but_do_not_chase() {
+        let mut g = Game::new_free(3, 64, 64, 0);
+        let c = g.dwarf_caves[0].clone();
+        // an ogre of the player walks into the cave
+        let id = g.spawn(EK::Ogre, false, c.at.0 as f32 + 0.5, c.at.1 as f32 + 0.5, 3);
+        let mut hit = false;
+        for _ in 0..(20 * 20) {
+            g.update(0.05);
+            if let Some(j) = g.find(id) {
+                hit |= g.ents[j].hp < g.ents[j].max_hp;
+            }
+        }
+        assert!(hit, "the dwarves attack");
+        let home = (c.at.0 as f32 + 0.5, c.at.1 as f32 + 0.5);
+        for e in g.ents.iter().filter(|e| e.alive && e.dwarf()) {
+            let d = ((e.x - home.0).powi(2) + (e.y - home.1).powi(2)).sqrt();
+            assert!(d < LEASH + 2.5, "dwarf strayed {:.1} tiles", d);
+        }
+    }
+
+    #[test]
+    fn dwarves_grow_with_the_army() {
+        let mut g = Game::new_free(5, 64, 64, 0);
+        let lvl = |g: &Game| g.ents.iter().filter(|e| e.alive && e.dwarf()).map(|e| e.level).sum::<u32>();
+        let before = lvl(&g);
+        let (cx, cy) = g.map.core;
+        for k in 0..8 {
+            g.spawn(EK::Ogre, false, cx as f32 + 1.0 + k as f32 * 0.2, cy as f32 - 1.0, 8);
+        }
+        g.dwarf_t = 0.0;
+        g.update_dwarves(0.1);
+        assert!(lvl(&g) > before);
+    }
+
+    #[test]
+    fn rune_chest_gives_a_free_tower_once() {
+        let mut g = Game::new_free(5, 64, 64, 0);
+        let (cx, cy) = g.map.core;
+        let (tx, ty) = (cx + 4, cy + 1);
+        g.map.t[idx(tx, ty)].kind = Kind::RuneChest;
+        g.map.t[idx(tx, ty)].owner = Owner::None;
+        g.open_rune_chest(idx(tx, ty));
+        assert_eq!(g.rune_available(), 1);
+        g.map.t[idx(tx, ty)].owner = Owner::Player;
+        let gold = g.gold;
+        g.build_tower(TowerKind::Rune, tx, ty);
+        assert_eq!(g.towers.len(), 1);
+        assert_eq!(g.gold, gold, "free");
+        assert_eq!(g.rune_available(), 0);
+        g.build_tower(TowerKind::Rune, tx + 1, ty);
+        assert_eq!(g.towers.len(), 1, "only one per chest");
+        // free play: selling gives the base tower back at once - but only once
+        g.sell_rect(tx, ty, tx, ty);
+        assert_eq!(g.rune_available(), 1);
+        g.build_tower(TowerKind::Rune, tx, ty);
+        assert!(g.towers[0].rune_final);
+        g.sell_rect(tx, ty, tx, ty);
+        assert_eq!(g.rune_available(), 0, "no second refund");
+        // in a mission the tower comes back in the next one
+        let mut m = crate::campaign::start_mission(0, None);
+        let (cx, cy) = m.map.core;
+        m.rune_free = 1;
+        m.build_tower(TowerKind::Rune, cx + 4, cy + 1);
+        assert_eq!(m.towers.len(), 1, "built in the mission");
+        m.sell_rect(cx + 4, cy + 1, cx + 4, cy + 1);
+        assert_eq!((m.rune_available(), m.rune_next), (0, 1));
+        let c = crate::campaign::carry_from(&m);
+        let next = crate::campaign::start_mission(1, Some(&c));
+        assert_eq!(next.rune_final, 1);
+    }
+
+    #[test]
+    fn imps_repair_towers_before_claiming() {
+        let mut g = Game::new(4, 64, 64);
+        let (cx, cy) = g.map.core;
+        // plenty of unclaimed floor next to the dungeon
+        for y in cy - 3..=cy + 5 {
+            for x in cx + 6..=cx + 12 {
+                g.map.t[idx(x, y)].kind = Kind::Floor;
+                g.map.t[idx(x, y)].owner = Owner::None;
+            }
+        }
+        let (tx, ty) = (cx + 4, cy - 2);
+        g.map.t[idx(tx, ty)].kind = Kind::Floor;
+        g.map.t[idx(tx, ty)].owner = Owner::Player;
+        g.build_tower(TowerKind::Arrow, tx, ty);
+        assert_eq!(g.towers.len(), 1);
+        g.towers[0].hp = 50.0;
+        let gold = g.gold;
+        for _ in 0..(20 * 20) {
+            g.update(0.05);
+        }
+        assert!(g.towers[0].hp >= g.towers[0].max_hp() - 1.0, "repaired: {}", g.towers[0].hp);
+        assert!(g.gold >= gold - 1.0, "repairs are free");
+    }
+
+    #[test]
+    fn missions_have_dwarf_caves() {
+        let mut total = 0;
+        for i in 0..crate::campaign::missions().len() {
+            let g = crate::campaign::start_mission(i, None);
+            total += g.dwarf_caves.len();
+        }
+        println!("{} dwarf caves in the campaign", total);
+        assert!(total >= 20);
+    }
+}

src/fortress.rs

@@ -134,7 +134,7 @@ impl Game {
             let id = self.next_id;
             self.next_id += 1;
             let s = tower_stats(kind);
-            let mut tw = Tower { id, kind, tile: i, level: 1, hp: s.hp, cd: 1.0, aim: 0.0, flash: 0.0, hero: true };
+            let mut tw = Tower { id, kind, tile: i, level: 1, hp: s.hp, cd: 1.0, aim: 0.0, flash: 0.0, hero: true, rune_final: false };
             while tw.level < f.tower_level.min(3) {
                 let old = tw.max_hp();
                 tw.level += 1;

src/game.rs

@@ -120,6 +120,8 @@ pub struct St {
     pub bounty: i32,
 }
 
+pub const RUNE_TOOL: usize = 20; // index of the rune forge tower in ui::TOOLS
+
 pub fn st(k: EK) -> St {
     let s = |name, hp, atk, range, speed, interval, wage, bounty| St { name, hp, atk, range, speed, interval, wage, bounty };
     match k {
@@ -322,7 +324,11 @@ impl Ent {
     }
     // a unit of a rival master
     pub fn rival(&self) -> bool {
-        !self.hero && self.side >= 2
+        !self.hero && (self.side == 2 || self.side == 3)
+    }
+    // a dwarf of a dwarf cave (neutral, never an opponent for victory)
+    pub fn dwarf(&self) -> bool {
+        !self.hero && self.side == crate::dwarves::DWARF_SIDE
     }
     // a hero that is still fighting (not a prisoner)
     pub fn active_hero(&self) -> bool {
@@ -436,6 +442,16 @@ pub struct Game {
     #[serde(skip)]
     pub springs: usize, // claimed mana springs (recounted)
     #[serde(default)]
+    pub dwarf_caves: Vec<crate::dwarves::DwarfCave>,
+    #[serde(default)]
+    pub dwarf_t: f32,
+    #[serde(default)]
+    pub rune_free: u32, // rune forge towers that can be built for free (from chests)
+    #[serde(default)]
+    pub rune_final: u32, // the same, but given back for a sold tower: no second refund
+    #[serde(default)]
+    pub rune_next: u32, // sold rune forge towers: back as a chest in the next mission
+    #[serde(default)]
     pub freed: u32, // chained creatures freed // tiles next to fighting heroes: knight ground there cannot be claimed
     #[serde(skip)]
     pub hints: bool, // show hint messages (setting)
@@ -511,6 +527,7 @@ impl Game {
         let dist = ((gx - cx).abs() + (gy - cy).abs()) as f32;
         g.wave_timer = FIRST_WAVE + ((dist - 45.0) * 1.5).clamp(0.0, 300.0);
         g.guard_treasures();
+        g.place_dwarf_caves(seed);
         g.msg("msg.welcome1", vec![]);
         g.msg("msg.welcome2", vec![]);
         g.msg("msg.welcome3", vec![]);
@@ -582,6 +599,11 @@ impl Game {
             gate_on: true,
             springs: 0,
             freed: 0,
+            dwarf_caves: Vec::new(),
+            dwarf_t: 30.0,
+            rune_free: 0,
+            rune_final: 0,
+            rune_next: 0,
         };
         let (cx, cy) = g.map.core;
         // the soul core starts surrounded by a one tile wide ring of treasury
@@ -615,6 +637,11 @@ impl Game {
 
     // ---------------------------------------------------------------- campaign missions
 
+    // the rune forge tower only shows up in the build menu once there is one to build or upgrade
+    pub fn tool_visible(&self, tool: usize) -> bool {
+        tool != RUNE_TOOL || self.rune_available() > 0 || self.towers.iter().any(|t| !t.hero && t.kind == TowerKind::Rune)
+    }
+
     pub fn tool_allowed(&self, tool: usize) -> bool {
         self.mission.as_ref().map_or(true, |m| m.tools.get(tool).copied().unwrap_or(true))
     }
@@ -989,6 +1016,7 @@ impl Game {
         if !self.rivals.is_empty() {
             self.update_rivals(dt);
         }
+        self.update_dwarves(dt);
         self.check_end();
     }
 
@@ -1357,7 +1385,7 @@ impl Game {
     }
 
     // strength of a squad (same formula as the army value)
-    fn squad_value(list: &[(EK, u32)]) -> f32 {
+    pub(crate) fn squad_value(list: &[(EK, u32)]) -> f32 {
         let (mut h, mut d) = (0.0, 0.0);
         for &(k, l) in list {
             let s = st(k);
@@ -1574,6 +1602,8 @@ impl Game {
             self.captive_update(e, dt);
         } else if e.rival() {
             self.rival_ai(e, dt);
+        } else if e.dwarf() {
+            self.dwarf_ai(e, dt);
         } else if e.hero {
             self.hero_ai(e, dt);
         } else if e.kind == EK::Worker {
@@ -1900,6 +1930,10 @@ impl Game {
             self.fx(5, x, y, 0.0, 0.0, 1.0, 0xff30d0ff);
             self.sfx(Sfx::HeroDeath, x, y);
             self.msg("msg.hero_slain", vec![format!("@{}", s.name), (got as i32).to_string()]);
+        } else if side == crate::dwarves::DWARF_SIDE {
+            let got = self.add_gold(s.bounty as f32 * 0.5);
+            self.sfx(Sfx::HeroDeath, x, y);
+            self.msg("msg.dwarf_slain", vec![(got as i32).to_string()]);
         } else if side >= 2 {
             // a creature of a rival master: half its wage as booty
             let got = self.add_gold(s.wage as f32 * 0.5);
@@ -2161,6 +2195,9 @@ impl Game {
             self.sfx(Sfx::Magic, x, y);
             self.msg("msg.spring_taken", vec![]);
         }
+        if t.kind == Kind::RuneChest {
+            self.open_rune_chest(i);
+        }
         if t.kind == Kind::Shard {
             self.shards_taken += 1;
             self.fx(7, x, y, 0.0, 0.0, 1.2, 0xff6060ff);
@@ -2169,6 +2206,16 @@ impl Game {
         }
     }
 
+    // a dwarven chest: the plans of a rune forge tower (one free build)
+    pub fn open_rune_chest(&mut self, i: usize) {
+        let (x, y) = (xy(i).0 as f32 + 0.5, xy(i).1 as f32 + 0.5);
+        self.map.t[i].kind = Kind::Floor;
+        self.rune_free += 1;
+        self.fx(7, x, y, 0.0, 0.0, 1.4, 0xff40c0ff);
+        self.sfx(Sfx::LevelUp, x, y);
+        self.msg("msg.rune_chest", vec![]);
+    }
+
     // a fortress unit spotted an enemy: guards and patrols nearby join the fight
     fn alarm(&mut self, x: f32, y: f32, target: u32) {
         for o in self.ents.iter_mut() {
@@ -2294,7 +2341,7 @@ impl Game {
     fn claimable(&self, i: usize, me: u32) -> bool {
         let t = &self.map.t[i];
         let ok = match t.owner {
-            Owner::None => matches!(t.kind, Kind::Floor | Kind::Portal | Kind::Bridge | Kind::LavaBridge | Kind::Shard | Kind::Treasury | Kind::ManaSpring),
+            Owner::None => matches!(t.kind, Kind::Floor | Kind::Portal | Kind::Bridge | Kind::LavaBridge | Kind::Shard | Kind::Treasury | Kind::ManaSpring | Kind::RuneChest),
             // knight ground (also vaults and shard chambers), but not while heroes fight there
             // knight and rival ground (also vaults and shard chambers), but not while enemies fight there
             Owner::Hero | Owner::Rival1 | Owner::Rival2 => {
@@ -2604,13 +2651,7 @@ impl Game {
                 if e.carry > 0 && self.start_deliver(e) {
                     return;
                 }
-                if let Some(p) = self.map.search(cur, self.map.walk_cost(), |i| self.claimable(i, me), true) {
-                    let end = p.last().copied().unwrap_or(cur);
-                    self.map.t[end].reserved = me;
-                    e.path = p;
-                    e.job = Job::Claim(end);
-                    return;
-                }
+                // damaged towers are repaired (free of charge) before more ground is claimed
                 if let Some(p) = self.map.search(cur, self.map.walk_cost(), |i| self.damaged_tower_near(i).is_some(), true) {
                     let end = p.last().copied().unwrap_or(cur);
                     if let Some(id) = self.damaged_tower_near(end) {
@@ -2619,6 +2660,13 @@ impl Game {
                         return;
                     }
                 }
+                if let Some(p) = self.map.search(cur, self.map.walk_cost(), |i| self.claimable(i, me), true) {
+                    let end = p.last().copied().unwrap_or(cur);
+                    self.map.t[end].reserved = me;
+                    e.path = p;
+                    e.job = Job::Claim(end);
+                    return;
+                }
                 if let Some(p) = self.map.search(cur, self.map.walk_cost(), |i| self.reinforce_neighbor(i, me).is_some(), true) {
                     let end = p.last().copied().unwrap_or(cur);
                     if let Some(w) = self.reinforce_neighbor(end, me) {
@@ -3662,6 +3710,16 @@ impl Game {
                 let i = idx(x, y);
                 if let Some(k) = self.towers.iter().position(|t| t.tile == i && !t.hero) {
                     refund += self.towers[k].invested() as f32 * 0.5;
+                    if self.towers[k].kind == TowerKind::Rune && !self.towers[k].rune_final {
+                        // the base tower comes back once: in the next mission (free play: at once)
+                        if self.mission.is_some() {
+                            self.rune_next += 1;
+                            self.msg("msg.rune_next", vec![]);
+                        } else {
+                            self.rune_final += 1;
+                            self.msg("msg.rune_back", vec![]);
+                        }
+                    }
                     self.towers.remove(k);
                     self.map.t[i].kind = Kind::Floor;
                     continue;
@@ -3758,11 +3816,25 @@ impl Game {
             self.sfx_ui(Sfx::Error);
             return;
         }
+        // rune forge towers: one build per opened chest (fresh plans first)
+        let mut rune_final = false;
+        if kind == TowerKind::Rune {
+            if self.rune_free > 0 {
+                self.rune_free -= 1;
+            } else if self.rune_final > 0 {
+                self.rune_final -= 1;
+                rune_final = true;
+            } else {
+                self.hint(24, "hint.rune_none");
+                self.sfx_ui(Sfx::Error);
+                return;
+            }
+        }
         self.gold -= cost;
         self.map.t[i].kind = Kind::Tower;
         let id = self.next_id;
         self.next_id += 1;
-        let tower = Tower { id, kind, tile: i, level: 1, hp: s.hp, cd: 1.0, aim: 0.0, flash: 0.0, hero: false };
+        let tower = Tower { id, kind, tile: i, level: 1, hp: s.hp, cd: 1.0, aim: 0.0, flash: 0.0, hero: false, rune_final };
         let (px, py) = tower.pos();
         self.towers.push(tower);
         // units standing on the tile step aside
@@ -3826,8 +3898,7 @@ impl Game {
         for (j, e) in self.ents.iter().enumerate() {
             // knight towers shoot the player's units, the player's towers shoot heroes
             // knight towers shoot everybody but the humans, the player's towers everybody else
-            let enemy = e.captive == 0 && !e.chained && if t.hero { e.side() != 1 } else { e.side() != 0 };
-            if !e.alive || e.held || !enemy {
+            if !e.alive || e.held || !self.tower_enemy(t, e) {
                 continue;
             }
             let d = (e.x - px).powi(2) + (e.y - py).powi(2);
@@ -3910,18 +3981,20 @@ impl Game {
             TowerKind::Arrow => (px, py, t.top() + 0.25),
             TowerKind::Cannon => (px + aim.cos() * 0.55, py + aim.sin() * 0.55, t.top() + 0.2),
             TowerKind::Magic => (px, py, t.top() + 0.45),
+            TowerKind::Rune => (px, py, t.top() + 0.55),
         };
         let col = match t.kind {
             TowerKind::Arrow => 0xffd0e0f0,
             TowerKind::Cannon => 0xff303030,
             TowerKind::Magic => 0xffff60d0,
+            TowerKind::Rune => 0xff40c0ff,
         };
         self.shot(mx, my, mh, ex, ey, eh, 0.3, col);
         self.fx_at(2, ex, ey, eh, 0.3, 0xffffffff);
         self.sfx(match t.kind {
             TowerKind::Arrow => Sfx::Shoot,
             TowerKind::Cannon => Sfx::Cannon,
-            TowerKind::Magic => Sfx::Magic,
+            TowerKind::Magic | TowerKind::Rune => Sfx::Magic,
         }, px, py);
         let dmg = t.dmg();
         match target {
@@ -3983,6 +4056,7 @@ impl Game {
                 TowerKind::Arrow => (px, py, t.top() + 0.25),
                 TowerKind::Cannon => (px + aim.cos() * 0.55, py + aim.sin() * 0.55, t.top() + 0.2),
                 TowerKind::Magic => (px, py, t.top() + 0.45),
+                TowerKind::Rune => (px, py, t.top() + 0.55),
             };
             let dmg = t.dmg();
             match t.kind {
@@ -4065,10 +4139,46 @@ impl Game {
                         }
                     }
                 }
+                TowerKind::Rune => {
+                    // a rune bolt that jumps on to up to three more enemies nearby
+                    self.shot(mx, my, mh, ex, ey, 0.45, 0.25, 0xff40c0ff);
+                    self.fx(2, ex, ey, 0.0, 0.0, 0.35, 0xffffc040);
+                    self.sfx(Sfx::Magic, px, py);
+                    let mut hit = vec![j];
+                    let (mut lx, mut ly) = (ex, ey);
+                    self.tower_damage(j, dmg);
+                    for n in 0..3 {
+                        let next = self
+                            .ents
+                            .iter()
+                            .enumerate()
+                            .filter(|(o, e)| !hit.contains(o) && e.alive && !e.held && self.tower_enemy(&t, e) && (e.x - lx).powi(2) + (e.y - ly).powi(2) < 3.5 * 3.5)
+                            .min_by(|a, b| {
+                                let da = (a.1.x - lx).powi(2) + (a.1.y - ly).powi(2);
+                                let db = (b.1.x - lx).powi(2) + (b.1.y - ly).powi(2);
+                                da.partial_cmp(&db).unwrap_or(std::cmp::Ordering::Equal)
+                            })
+                            .map(|(o, _)| o);
+                        let Some(o) = next else { break };
+                        let (ox, oy) = (self.ents[o].x, self.ents[o].y);
+                        self.fx(0, lx, ly, ox, oy, 0.25, 0xff40c0ff);
+                        hit.push(o);
+                        if self.ents[o].alive {
+                            self.tower_damage(o, dmg * (0.75 - 0.1 * n as f32));
+                        }
+                        lx = ox;
+                        ly = oy;
+                    }
+                }
             }
         }
     }
 
+    // a unit the tower shoots at
+    fn tower_enemy(&self, t: &Tower, e: &Ent) -> bool {
+        e.captive == 0 && !e.chained && if t.hero { e.side() != 1 } else { e.side() != 0 }
+    }
+
     // a hero attacks a tower; false = tower gone or unreachable
     fn attack_tower(&mut self, e: &mut Ent, id: u32, dt: f32) -> bool {
         let Some(k) = self.towers.iter().position(|t| t.id == id) else { return false };
@@ -4127,8 +4237,8 @@ impl Game {
         }
         let Some(j) = target.filter(|&j| j < self.ents.len() && self.ents[j].alive && !self.ents[j].held) else { return false };
         let e = &self.ents[j];
-        if e.rival() {
-            return false; // the rivals' creatures cannot be picked up
+        if e.rival() || e.dwarf() {
+            return false; // the rivals' creatures and the dwarves cannot be picked up
         }
         if e.hero {
             if e.captive != 1 {
@@ -4209,6 +4319,9 @@ impl Game {
     pub fn slap(&mut self, target: Option<usize>) -> u8 {
         let Some(j) = target.filter(|&j| j < self.ents.len() && self.ents[j].alive && !self.ents[j].held) else { return 0 };
         let (x, y) = (self.ents[j].x, self.ents[j].y);
+        if self.ents[j].dwarf() {
+            return 0;
+        }
         if !self.ents[j].hero && !self.ents[j].rival() {
             let e = &mut self.ents[j];
             e.boost = 15.0;
@@ -4323,6 +4436,7 @@ pub enum TowerKind {
     Arrow,
     Cannon,
     Magic,
+    Rune, // dwarven rune forge tower: from a chest of a dwarf cave, built for free
 }
 
 pub struct TowerStats {
@@ -4340,6 +4454,7 @@ pub fn tower_stats(k: TowerKind) -> TowerStats {
         TowerKind::Arrow => TowerStats { cost: [250, 200, 300], hp: 300.0, dmg: 10.0, range: 6.0, min_range: 0.0, interval: 0.8, mana: 0.0 },
         TowerKind::Cannon => TowerStats { cost: [450, 350, 500], hp: 450.0, dmg: 32.0, range: 8.5, min_range: 2.0, interval: 2.6, mana: 0.0 },
         TowerKind::Magic => TowerStats { cost: [350, 300, 450], hp: 300.0, dmg: 24.0, range: 7.0, min_range: 0.0, interval: 1.5, mana: 8.0 },
+        TowerKind::Rune => TowerStats { cost: [0, 800, 1200], hp: 1400.0, dmg: 55.0, range: 10.0, min_range: 0.0, interval: 1.3, mana: 0.0 },
     }
 }
 
@@ -4348,6 +4463,7 @@ pub fn tower_name(k: TowerKind) -> &'static str {
         TowerKind::Arrow => "tower.arrow",
         TowerKind::Cannon => "tower.cannon",
         TowerKind::Magic => "tower.magic",
+        TowerKind::Rune => "tower.rune",
     }
 }
 
@@ -4363,6 +4479,8 @@ pub struct Tower {
     pub flash: f32,
     #[serde(default)]
     pub hero: bool, // tower of a knight fortress: shoots the player's units
+    #[serde(default)]
+    pub rune_final: bool, // rune forge tower built from a refund: selling it gives nothing back
 }
 
 impl Tower {
@@ -4386,6 +4504,7 @@ impl Tower {
             TowerKind::Arrow => 1.0 + 0.3 * (self.level - 1) as f32,
             TowerKind::Cannon => 0.6 + 0.15 * (self.level - 1) as f32,
             TowerKind::Magic => 1.2 + 0.3 * (self.level - 1) as f32,
+            TowerKind::Rune => 1.4 + 0.25 * (self.level - 1) as f32,
         }
     }
     // gold spent on this tower so far
@@ -4615,7 +4734,9 @@ mod tests {
         g.gold = g.gold_cap();
         g.update(0.01);
         assert!((treasury_total(&g) - g.gold).abs() < 2.0);
-        assert!(g.reserve > 0.0 && g.reserve <= CORE_STORE + 1.0);
+        // (tiles partly filled with rubies take no gold, so the core may hold a little more)
+        let gem_room: f32 = g.map.t.iter().filter(|t| t.kind == Kind::Treasury && t.owner == Owner::Player && t.res != 0).map(|t| TREASURY_TILE - t.gold as f32).sum();
+        assert!(g.reserve > 0.0 && g.reserve <= CORE_STORE + gem_room + 1.0, "reserve {} gold {} cap {}", g.reserve, g.gold, g.gold_cap());
     }
 
     #[test]

src/gfx.rs

@@ -69,6 +69,7 @@ pub const T_STEEL: u32 = 130; // 4 variants: riveted iron plates
 pub const I_STEEL: u32 = 134;
 pub const T_RIVAL1: u32 = 135; // 4 variants: floor of the green master
 pub const T_RIVAL2: u32 = 139; // 4 variants: floor of the blue master
+pub const I_RUNE: u32 = 143; // rune forge tower
 
 pub struct Gfx {
     pub atlas: Texture2D,
@@ -570,6 +571,23 @@ fn gen_atlas() -> Image {
             None
         }
     });
+    cv.cell(I_RUNE, |x, y| {
+        // a stone obelisk with a glowing rune, bronze bands
+        let body = (5..=10).contains(&x) && y >= 3 && y <= 14 && !(y == 3 && (x == 5 || x == 10));
+        if !body {
+            return None;
+        }
+        let rune = (x == 7 || x == 8) && (6..=10).contains(&y) || (y == 8 && (6..=9).contains(&x));
+        Some(if rune {
+            c(90, 210, 255)
+        } else if y == 4 || y == 12 {
+            c(190, 120, 60)
+        } else if (x + y) % 5 == 0 {
+            c(80, 80, 92)
+        } else {
+            c(110, 110, 124)
+        })
+    });
     cv.cell(I_SUMMON, |x, y| {
         let d = (((x - 8) * (x - 8) + (y - 8) * (y - 8)) as f32).sqrt();
         let a = ((y - 8) as f32).atan2((x - 8) as f32);
@@ -1383,6 +1401,7 @@ impl Gfx {
             Kind::Aerie => T_AERIE + v,
             Kind::Steel => T_STEEL + v,
             Kind::ManaSpring => T_PORTALFLOOR + v,
+            Kind::RuneChest => T_FLOOR + v,
         }
     }
 

src/main.rs

@@ -3,6 +3,7 @@
 mod audio;
 mod campaign;
 mod cloud;
+mod dwarves;
 mod fortress;
 mod game;
 mod gfx;

src/map.rs

@@ -60,13 +60,14 @@ pub enum Kind {
     Aerie,      // room for flying creatures (their beds)
     Steel,      // steel wall: hardly anyone gets through
     ManaSpring, // crystal spring: once claimed, more mana and a higher mana maximum
+    RuneChest,  // dwarven chest with the plans of a rune forge tower (claim it: one free build)
 }
 
 // options for the map generator (campaign missions)
 #[derive(Clone, Debug)]
 pub struct GenOpts {
     pub portals: Option<usize>,   // None: one per 64 x 64 tiles
-    pub treasures: Option<usize>, // guarded treasure caves; None: portals - 1
+    pub treasures: Option<usize>, // knight treasure caves; None: none (free play has dwarf caves instead)
     pub gate: bool,               // hero gate at the far side
     pub core_y: Option<i32>,      // row of the core (None: about the middle)
 }
@@ -88,7 +89,7 @@ pub struct River {
 }
 
 // order matters for the packed savegame codec: only append new kinds
-const KINDS: [Kind; 26] = [
+const KINDS: [Kind; 27] = [
     Kind::Rock,
     Kind::Earth,
     Kind::Gold,
@@ -115,6 +116,7 @@ const KINDS: [Kind; 26] = [
     Kind::Aerie,
     Kind::Steel,
     Kind::ManaSpring,
+    Kind::RuneChest,
 ];
 
 // treasures (veins, treasury content, imp loads): 0 gold, 1 silver, 2 ruby, 3 diamond
@@ -210,6 +212,7 @@ impl Tile {
                 | Kind::Shard
                 | Kind::Aerie
                 | Kind::ManaSpring
+                | Kind::RuneChest
         )
     }
     // river tiles (open, but nobody can walk there)
@@ -349,7 +352,7 @@ impl Map {
         let area = (w * h) as f32 / 4096.0;
         let scale = |n: f32| (n * area).round() as i32;
         let n_portals = opts.portals.unwrap_or((area.round() as usize).max(1));
-        let n_treasures = opts.treasures.unwrap_or(n_portals.saturating_sub(1));
+        let n_treasures = opts.treasures.unwrap_or(0);
 
         let mut t = vec![Tile::new(Kind::Earth); w * h];
         for (i, tile) in t.iter_mut().enumerate() {

src/props.rs

@@ -98,6 +98,7 @@ pub fn draw_props_solid(g: &Game, cam: &Cam, t: f32) {
                 Kind::Library if z % 2 == 0 => shelf(c, h, l),
                 Kind::Library if h % 3 == 0 => lectern(c, l),
                 Kind::ManaSpring => spring_basin(c, l),
+                Kind::RuneChest => rune_chest(c, l),
                 _ => {}
             }
         }
@@ -118,6 +119,16 @@ pub fn draw_props_solid(g: &Game, cam: &Cam, t: f32) {
     }
 }
 
+// the dwarves' iron-bound chest with the rune forge plans (the rune glows in the glow pass)
+fn rune_chest(c: Vec3, l: f32) {
+    cube(c + vec3(0.0, 0.16, 0.0), vec3(0.5, 0.3, 0.34), rgb(92, 60, 34, l));
+    cube(c + vec3(0.0, 0.34, 0.0), vec3(0.52, 0.08, 0.36), rgb(110, 72, 40, l));
+    for dx in [-0.18f32, 0.18] {
+        cube(c + vec3(dx, 0.2, 0.0), vec3(0.05, 0.4, 0.38), rgb(176, 112, 56, l));
+    }
+    cube(c + vec3(0.0, 0.22, 0.18), vec3(0.08, 0.1, 0.03), rgb(200, 170, 80, l));
+}
+
 // a stone basin around a mana spring
 fn spring_basin(c: Vec3, l: f32) {
     for (dx, dz, sx, sz) in [(0.0, -0.38, 0.8, 0.1), (0.0, 0.38, 0.8, 0.1), (-0.38, 0.0, 0.1, 0.8), (0.38, 0.0, 0.1, 0.8)] {
@@ -183,6 +194,11 @@ pub fn draw_props_glow(g: &Game, cam: &Cam, t: f32) {
                         }
                     }
                 }
+                Kind::RuneChest => {
+                    let f = 0.6 + 0.4 * (t * 2.5 + k).sin();
+                    draw_cube(c + vec3(0.0, 0.39, 0.0), vec3(0.14, 0.02, 0.14), None, Color::new(0.35, 0.8, 1.0, f));
+                    draw_sphere(c + vec3(0.0, 0.45, 0.0), 0.2, None, Color::new(0.3, 0.7, 1.0, 0.15 * f));
+                }
                 Kind::ManaSpring => {
                     // rising mana: a pulsing pool and motes that drift up
                     let f = 0.8 + 0.2 * (t * 2.0 + k).sin();

src/render3d.rs

@@ -1347,6 +1347,34 @@ fn draw_towers_solid(g: &Game) {
                     bx(vec3(dx, h + 0.12, dz), vec3(0.06, 0.18, 0.06), col(120, 104, 140));
                 }
             }
+            TowerKind::Rune => {
+                // dwarven rune forge: broad granite foot, bronze bands, a tapering keep with
+                // carved buttresses, an anvil crown and a forge hearth on top (runes glow)
+                bx(vec3(0.0, 0.07, 0.0), vec3(0.96, 0.14, 0.96), col(70, 66, 70));
+                bx(vec3(0.0, 0.19, 0.0), vec3(0.84, 0.1, 0.84), col(84, 80, 86));
+                let steps = 5;
+                for k in 0..steps {
+                    let y0 = 0.24 + (h - 0.24) * k as f32 / steps as f32;
+                    let hh = (h - 0.24) / steps as f32;
+                    let w = 0.72 - k as f32 * 0.05;
+                    bx(vec3(0.0, y0 + hh * 0.5, 0.0), vec3(w, hh + 0.005, w), col(96 - k as u8 * 2, 92 - k as u8 * 2, 98));
+                    bx(vec3(0.0, y0 + 0.01, 0.0), vec3(w + 0.03, 0.035, w + 0.03), shade_c(176, 112, 56, f));
+                }
+                for (dx, dz) in [(0.38f32, 0.38f32), (-0.38, 0.38), (0.38, -0.38), (-0.38, -0.38)] {
+                    bx(vec3(dx, h * 0.3, dz), vec3(0.14, h * 0.6, 0.14), col(78, 74, 80));
+                    bx(vec3(dx, h * 0.6 + 0.05, dz), vec3(0.17, 0.08, 0.17), shade_c(176, 112, 56, f));
+                }
+                // gate with a bronze door
+                bx(vec3(0.0, 0.42, 0.37), vec3(0.26, 0.4, 0.04), shade_c(120, 76, 40, f));
+                bx(vec3(0.0, 0.64, 0.38), vec3(0.32, 0.06, 0.05), col(110, 106, 112));
+                // anvil crown and hearth
+                bx(vec3(0.0, h + 0.05, 0.0), vec3(0.62, 0.1, 0.62), col(60, 58, 64));
+                bx(vec3(0.0, h + 0.16, 0.0), vec3(0.3, 0.12, 0.42), col(48, 48, 54));
+                bx(vec3(0.0, h + 0.25, 0.0), vec3(0.42, 0.08, 0.56), col(56, 56, 62));
+                for (dx, dz) in [(-0.27f32, -0.27f32), (0.27, -0.27), (0.27, 0.27), (-0.27, 0.27)] {
+                    bx(vec3(dx, h + 0.16, dz), vec3(0.08, 0.22, 0.08), shade_c(176, 112, 56, f));
+                }
+            }
         }
         // level pips on the plinth
         for k in 0..tw.level {
@@ -1357,6 +1385,29 @@ fn draw_towers_solid(g: &Game) {
 
 fn draw_towers_glow(g: &Game, t: f32) {
     for (k, tw) in g.towers.iter().enumerate() {
+        if tw.kind == TowerKind::Rune {
+            // forge glow on the crown, runes on the keep and three rune stones circling it
+            let (x, z) = tw.pos();
+            let h = tower_height(tw);
+            let pulse = 1.0 + (t * 3.0 + k as f32).sin() * 0.12 + tw.flash * 2.5;
+            draw_sphere(vec3(x, h + 0.34, z), 0.1 * pulse, None, Color::new(1.0, 0.75, 0.3, 0.95));
+            draw_sphere(vec3(x, h + 0.36, z), 0.24 * pulse, None, Color::new(1.0, 0.55, 0.15, 0.22));
+            for r in 0..4 {
+                let y = 0.4 + (h - 0.5) * r as f32 / 4.0;
+                let glow = 0.35 + 0.65 * ((t * 2.0 - r as f32 * 0.9 + k as f32).sin() * 0.5 + 0.5);
+                let w = 0.72 - r as f32 * 0.05;
+                for (dx, dz) in [(w * 0.5 + 0.01, 0.0f32), (-w * 0.5 - 0.01, 0.0), (0.0, w * 0.5 + 0.01), (0.0, -w * 0.5 - 0.01)] {
+                    draw_cube(vec3(x + dx, y + 0.1, z + dz), vec3(if dx == 0.0 { 0.12 } else { 0.02 }, 0.1, if dz == 0.0 { 0.12 } else { 0.02 }), None, Color::new(0.35, 0.8, 1.0, glow));
+                }
+            }
+            for n in 0..(2 + tw.level) {
+                let a = t * 1.2 + n as f32 * std::f32::consts::TAU / (2 + tw.level) as f32;
+                let p = vec3(x + a.cos() * 0.62, h * 0.7 + (t * 2.0 + n as f32).sin() * 0.08, z + a.sin() * 0.62);
+                draw_cube(p, vec3(0.1, 0.12, 0.1), None, Color::new(0.3, 0.75, 1.0, 0.9));
+                draw_sphere(p, 0.12, None, Color::new(0.3, 0.7, 1.0, 0.2));
+            }
+            continue;
+        }
         if tw.kind != TowerKind::Magic {
             continue;
         }
@@ -1595,6 +1646,8 @@ fn draw_shadows(g: &Game) {
         disc(vec3(e.x, 0.012, e.y), r, Color::new(0.0, 0.0, 0.0, 0.4), 12);
         let rc = if e.captive != 0 {
             Color::new(0.6, 0.6, 0.6, 0.6)
+        } else if e.dwarf() {
+            Color::new(0.85, 0.55, 0.25, 0.85)
         } else if e.rival() {
             if e.side == 2 {
                 Color::new(0.35, 0.95, 0.4, 0.85)
@@ -1806,6 +1859,7 @@ pub fn minimap_color(tile: &Tile) -> [u8; 4] {
         Kind::Aerie => [170, 140, 90, 255],
         Kind::Steel => [150, 160, 180, 255],
         Kind::ManaSpring => [90, 230, 255, 255],
+        Kind::RuneChest => [80, 200, 255, 255],
     }
 }
 

src/rival.rs

@@ -85,6 +85,7 @@ impl Game {
         g.msg("msg.welcome1", vec![]);
         g.msg("msg.welcome2", vec![]);
         g.msg(if rivals == 0 { "msg.welcome_humans" } else if humans { "msg.welcome_both" } else { "msg.welcome_rivals" }, vec![rivals.to_string()]);
+        g.place_dwarf_caves(seed);
         g
     }
 
@@ -267,7 +268,7 @@ impl Game {
         }
     }
 
-    fn eliminate_rival(&mut self, k: usize) {
+    pub(crate) fn eliminate_rival(&mut self, k: usize) {
         let side = self.rivals[k].side;
         let owner = Owner::of_side(side);
         self.rivals[k].alive = false;

src/save.rs

@@ -98,7 +98,8 @@ mod tests {
         let mut g = Game::new(7, 256, 256);
         let gen = t0.elapsed();
         assert_eq!(g.map.portals.len(), 16);
-        assert_eq!(g.map.treasures.len(), 15);
+        assert_eq!(g.map.treasures.len(), 0); // knight caves are replaced by dwarf caves
+        assert!((1..=4).contains(&g.dwarf_caves.len()));
         let (cx, cy) = g.map.core;
         g.mark_rect(cx - 5, cy - 5, cx + 8, cy + 8, true);
         let t1 = std::time::Instant::now();

src/settings.rs

@@ -25,7 +25,7 @@ pub enum Action {
 }
 
 pub fn all_actions() -> Vec<Action> {
-    let mut v: Vec<Action> = (0..20).map(Action::Tool).collect();
+    let mut v: Vec<Action> = (0..21).map(Action::Tool).collect();
     v.extend_from_slice(&[
         Action::CamForward,
         Action::CamBack,
@@ -70,7 +70,7 @@ impl Action {
     fn default_key(self) -> KeyCode {
         use KeyCode::*;
         match self {
-            Action::Tool(i) => [Key1, Key2, Key3, Key4, Key5, Key6, Key7, Key8, Key9, Key0, X, V, K, J, B, C, T, U, Y, O][i.min(19)],
+            Action::Tool(i) => [Key1, Key2, Key3, Key4, Key5, Key6, Key7, Key8, Key9, Key0, X, V, K, J, B, C, T, U, Y, O, N][i.min(20)],
             Action::CamForward => W,
             Action::CamBack => S,
             Action::CamLeft => A,

src/ui.rs

@@ -160,7 +160,7 @@ pub enum Tool {
 }
 
 // New tools are appended so that existing key bindings ("tool<i>") keep their meaning
-pub const TOOLS: [Tool; 20] = [
+pub const TOOLS: [Tool; 21] = [
     Tool::Dig,
     Tool::Hand,
     Tool::Room(0),
@@ -181,6 +181,7 @@ pub const TOOLS: [Tool; 20] = [
     Tool::Bridge,
     Tool::Room(7),
     Tool::Steel,
+    Tool::Tower(TowerKind::Rune),
 ];
 
 
@@ -206,6 +207,7 @@ pub fn tool_info(t: Tool) -> ToolInfo {
         Tool::Tower(TowerKind::Arrow) => ("arrow", I_ARROW, None),
         Tool::Tower(TowerKind::Cannon) => ("cannon", I_CANNON, None),
         Tool::Tower(TowerKind::Magic) => ("magic", I_MAGIC, None),
+        Tool::Tower(TowerKind::Rune) => ("rune", I_RUNE, None),
         Tool::Sell => ("sell", I_SELL, None),
         Tool::Flag => ("flag", I_FLAG, None),
         Tool::Lightning => ("lightning", I_BOLT, None),
@@ -229,6 +231,10 @@ pub fn tool_cost(t: Tool, g: &Game) -> String {
         Tool::Summon => trf("cost.mana", &[(g.summon_cost() as i32).to_string()]),
         Tool::Bridge => trf("cost.bridge", &[BRIDGE_COST[0].to_string(), BRIDGE_COST[1].to_string()]),
         Tool::Steel => trf("cost.steel", &[STEEL_COST[0].to_string(), STEEL_COST[1].to_string()]),
+        Tool::Tower(TowerKind::Rune) => {
+            let s = tower_stats(TowerKind::Rune);
+            trf("cost.rune", &[g.rune_available().to_string(), s.cost[1].to_string(), s.cost[2].to_string()])
+        }
         Tool::Tower(k) => {
             let s = tower_stats(k);
             let mut c = trf("cost.tower", &[s.cost[0].to_string(), s.cost[1].to_string(), s.cost[2].to_string()]);
@@ -246,7 +252,7 @@ pub const CATS: [(&str, &[usize]); 6] = [
     ("cat.dig", &[0]),
     ("cat.hand", &[1]),
     ("cat.rooms", &[2, 3, 4, 5, 6, 12, 13, 18, 17]),
-    ("cat.towers", &[14, 15, 16]),
+    ("cat.towers", &[14, 15, 16, 20]),
     ("cat.spells", &[9, 10, 11]),
     ("cat.orders", &[8, 7, 19]),
 ];
@@ -654,6 +660,8 @@ impl Ui {
             if e.alive && !e.held {
                 let c = if e.hero {
                     Color::new(0.6, 0.85, 1.0, 1.0)
+                } else if e.dwarf() {
+                    Color::new(0.85, 0.55, 0.25, 1.0)
                 } else if e.rival() {
                     if e.side == 2 {
                         Color::new(0.3, 0.95, 0.4, 1.0)
@@ -762,7 +770,7 @@ impl Ui {
 
         // the open row of tools (wraps into several rows if needed)
         if let Some((c, x0, bw, bcols)) = popup {
-            let tools = CATS[c].1;
+            let tools: Vec<usize> = CATS[c].1.iter().copied().filter(|&i| g.tool_visible(i)).collect();
             let per_row = (((cols - 2) as f32 / bcols).floor() as usize).max(1).min(tools.len());
             let nrows = (tools.len() + per_row - 1) / per_row;
             let pw = per_row as f32 * bw + 2.0 * CW();
@@ -1052,6 +1060,11 @@ pub fn hover_info(g: &Game, ent: Option<usize>, tile: Option<(i32, i32)>) -> Vec
             out.push((tr(["", "info.unconscious", "info.carried", "info.tortured"][e.captive.min(3) as usize]), RED));
             return out;
         }
+        if e.dwarf() {
+            out.push((tr("info.dwarf"), Color::new(0.9, 0.6, 0.3, 1.0)));
+            out.push((tr("info.dwarf_neutral"), DIM));
+            return out;
+        }
         out.push((tr(job_name(e)), TXT));
         if e.hero {
             out.push((tr(if e.guard { "info.guard" } else { "info.intruder" }), BLUE));
@@ -1136,6 +1149,10 @@ pub fn hover_info(g: &Game, ent: Option<usize>, tile: Option<(i32, i32)>) -> Vec
             out.push((tr("tile.shard"), RED));
             out.push((tr("tile.shard_info"), DIM));
         }
+        Kind::RuneChest => {
+            out.push((tr("tile.rune_chest"), BLUE));
+            out.push((tr("tile.rune_chest_info"), DIM));
+        }
         Kind::Gate => {
             out.push((tr("tile.gate"), BLUE));
             out.push((trf("info.hp", &[(g.gate_hp as i32).to_string(), (GATE_HP as i32).to_string()]), BLUE));