feat: extend mimics with Mimics.floorItem and Mimics.reveal

src/mimics.lua

@@ -0,0 +1,60 @@
+-- A mimic disguises itself as ordinary loot until a hand reaches for it.
+-- Builder.build drops one as a plain floorItem tagged `mimic = true`,
+-- wearing a random disguise's name and glyph (Mimics.DISGUISES) - utterly
+-- indistinguishable at rest from a real item, since render.lua and
+-- Game:pickupHere both just read an ordinary floorItem's own `.item.glyph`
+-- and `.item.name`, with no idea a given tile might be a trap. The instant
+-- the player steps onto it (Game:triggerMimic, called from pickupHere),
+-- Mimics.reveal builds the real hostile monster underneath, scaled by
+-- depth the same way Monsters.create scales a wild species's hp, and gets
+-- one free ambush swing in (via combat.lua, so it still respects the
+-- player's defense and resistances) before it settles into an ordinary
+-- chase like any other monster on its own turns from then on.
+
+local Entity = require("entity")
+local Factions = require("factions")
+
+local Mimics = {}
+
+Mimics.FACTION = Factions.BEAST
+
+Mimics.DISGUISES = {
+  { name = "a weathered chest", glyph = "=" },
+  { name = "a glinting pile of gold", glyph = "$" },
+  { name = "an ornate tome", glyph = "&" },
+  { name = "a discarded shield", glyph = "[" },
+}
+
+-- The inert floorItem a builder drops: it looks exactly like whichever
+-- disguise it rolled until Game:pickupHere unmasks it.
+function Mimics.floorItem(rng)
+  local disguise = Mimics.DISGUISES[rng:range(1, #Mimics.DISGUISES)]
+  return { kind = "mimic", mimic = true, name = disguise.name, glyph = disguise.glyph }
+end
+
+-- The hostile monster a disguised item becomes the instant it is
+-- disturbed, its hp scaled by depth exactly the way Monsters.create scales
+-- a wild species's own base hp.
+function Mimics.reveal(id, x, y, depth)
+  local bonusHp = depth - 1
+  local entity = Entity.new({
+    id = id, x = x, y = y,
+    glyph = "M", name = "mimic", kind = "monster",
+    species = "mimic", ai = "chase",
+    hp = 12 + bonusHp, maxHp = 12 + bonusHp,
+    attack = 5, defense = 1, speed = 100,
+  })
+  entity.cooldown = 0
+  entity.faction = Mimics.FACTION
+  entity.mimic = true
+  return entity
+end
+
+-- Flat xp reward for felling a revealed mimic - kept separate from
+-- Monsters.xpFor since a mimic is never a member of the wild bestiary
+-- Monsters.forDepth draws its ordinary per-floor population from.
+function Mimics.xpFor()
+  return 10
+end
+
+return Mimics