Roadmap: giant mushrooms for wood underground, raising walls

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

docs/ROADMAP.md

@@ -31,12 +31,16 @@ Stone bridges over lava exist already (75 gold per tile).
 
 1. **Surface terrain** – grass, trees, paths, daylight and sky. Trees act like earth: imps fell
    them.
-2. **Wood** – a second resource from felled trees. Wooden bridges, doors, siege engines and room
-   upgrades cost wood.
-3. **Fortresses above ground** – walls, towers, a gate, a clearing with torches.
-4. **Siege weapons** – heroes bring battering rams (against doors) and catapults (against towers);
+2. **Wood** – a second resource. Above ground it comes from trees (plenty: a fortress is besieged
+   there), underground from giant mushrooms in caves and by the water (scarce, slowly growing back,
+   so few wooden doors down there). Wooden bridges, wooden doors, siege engines and room upgrades
+   cost wood; iron and magic doors and stone bridges still cost gold.
+3. **Raising walls** – imps can raise a wall again on the player's own empty floor, for gold, so
+   tunnels can be closed and doors placed where they matter.
+4. **Fortresses above ground** – walls, towers, a gate, a clearing with torches.
+5. **Siege weapons** – heroes bring battering rams (against doors) and catapults (against towers);
    the player builds his own siege engines in a workshop.
-5. **Missions** – the last mission of the main campaign (M30) and of the co-op campaign (M20) lead
+6. **Missions** – the last mission of the main campaign (M30) and of the co-op campaign (M20) lead
    to the surface: the dungeon half lies in the rock (gold and more), the other half is a forest
    with the High Marshal's fortress to destroy. Free play and multiplayer get a map option
    "Surface". The map editor gets the new terrain.