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name: game-content description: Add or change content in the OSRS tower-defense game — an enemy, boss, tower, spell, prayer, item, drop table, relic or draft card — and the OSRS asset pipeline that bakes its sprites and sounds from the local game cache. Use when adding new game content, when a union type in lib/game/types.ts needs a new member, when a sprite or sound is missing, or when a wiki-hot-linked asset should be replaced with a real one.

Adding content

Static content is data, not code. It lives in lib/game/data/ (enemies.ts, towers.ts, waves.ts, gear.ts, prayers.ts, slayer.ts, ge.ts, combat-achievements.ts, biomes.ts, plus the baked enemy-anims*/spotanims* tables). Extend a table there rather than inlining anything in the engine.

Every new content id must also join its union type in lib/game/types.ts (EnemyType, TowerType, Element, AncientType, MageMode, PrayerType, …). TypeScript errors fail the build, so a missing union member surfaces immediately — but the union is what makes the exhaustive Record<> tables complain, so add it first and let the errors list every place that needs a value.

Checklists

New enemy or boss

1. data/enemies.ts — the stat block (hp, speed, reward, color, isBoss…).
2. EnemyType in types.ts.
3. data/drops.ts — its loot table (keyed by EnemyType).
4. Sprites: an entry in scripts/enemy-anims.config.json (npc id + anims ids for walk/hurt/death), then bake (below). Death sound: the engine plays death_<type>; wire it in core/sound.ts.
5. Wave presence: the procedural allocator (systems/wave-generation.ts) or data/waves.ts (LANDMARK_WAVES) for a scripted appearance.
6. Boss only: a mechanic in systems/boss-mechanics.ts — bosses are expected to have one.

New tower

1. data/towers.ts (the tier progression).
2. TowerType in types.ts.
3. systems/tower-identity.ts — its niche. Every tower must beat the wizard at something specific; the wizard already owns single-target and AoE. A tower with no signature is not finished.
4. lib/game/assets.ts — its per-tier sprite.
5. GameRoot.tsx — TOWER_ORDER, TOWER_COMBAT, and the dock grid (currently grid-cols-6 w-[17.5em]; a seventh tower means re-laying it out without changing the bar's height — see the game-ui skill).
6. A *.test.ts next to any pure logic you added in systems/.

New spell — systems/magic.ts (its hit/effect maths, with a test), plus the spell icon in assets.ts and its cast/impact sounds.

Assets come from OSRS itself

Hard rule: every asset is extracted or rendered from a local OSRS game cache. Never hot-link an external host, never invent a placeholder. If an asset can't be sourced, ask rather than substituting. assets.ts resolves every name to a local bake and assets.test.ts fails the build if a data table names an icon with none.

A cache is any folder holding main_file_cache.dat2 + main_file_cache.idx* — an installed RuneLite/Jagex client already has one. This machine has the cache and the deps: these scripts run here.

| What | Command | |---|---| | 2D interface sprites (prayer/skill icons, spellbooks, hitsplats) | npm run extract:sprites | | Sound effects | npm run extract:sounds | | Static NPC model portrait | npm run render:npcs | | Item inventory icons | node scripts/render-osrs-items.mjs | | Enemy animation clips (the real pipeline) | npm run export:enemy-gltf → npm run bake:enemies → npm run anims:data |

The enemy pipeline exports each NPC as an animated glTF, bakes walk/hurt/death sprite sheets from it with three.js (a real z-buffer, not the old hand-rolled rasteriser), then regenerates data/enemy-anims.data.ts from the manifests. Use --only <slug> to rebake one enemy.

Choosing which sequence id is a clip is its own job — hand it to the npc-anim-auditor subagent. Picking a hurt/death by reading the cache is a trap (an NPC's id block mixes its attacks, blocks and other rigs' anims; metrics can't tell an attack from a block), it takes dozens of probe images, and the agent already carries the method. Its anchor is npm run anims:observed — a cross-reference of the config against scripts/data/openosrs-observed-anims.json (the vendored OpenOSRS record of which sequences each NPC is actually seen playing in game), which flags configured ids the NPC never plays and lists the real candidates. Use the agent whenever an animation "looks wrong" or a new enemy needs clips.

Spot-anims (GFX) are baked by scripts/render-osrs-spotanims.mjs, but the flat rasteriser only handles geometry spotanims — textured ones come out as white boxes, so those stay procedural. Check the output PNG before persisting it. Same for tower/weapon renders: they must face side-on (ideally right); sweep the yaw and look at the PNG before committing.

Design direction

• Give systems personality. Prefer building new quests, achievements and pets over reviving the ones the old engine had.
• Make them challenging, and reward them with something other than money — do not inflate gold.
• The intended "main" mode is a roguelite with per-wave drafting (towers/upgrades/prayers/buffs/debuffs), alongside a pure tower-defense mode.

Verify it

New content is mostly data, so the typecheck catches structural mistakes and npx vitest run catches maths. Neither can tell you a sprite is facing the wrong way or an enemy never spawns — look at the baked PNG, and drive the game (see the game-verify skill). Balance is the user's job; don't propose a playtest plan.