Imported from openai/plugins (plugins/game-studio/skills/web-game-foundations/SKILL.md). Install upstream with npx skills add openai/plugins --skill web-game-foundations. Copyright stays with the author.

Web Game Foundations

Overview

Use this skill to establish the non-negotiable architecture before implementation starts. Browser games degrade quickly when simulation, rendering, UI, asset loading, and input handling are mixed together.

Default rule: simulation state is owned outside the renderer, browser UI is not forced into the canvas unless there is a clear reason, and shipped 3D assets default to GLB or glTF 2.0 rather than ad hoc model formats.

Use This Skill When

• the user has not settled the engine or renderer choice
• the task is about boundaries, module shape, state ownership, or asset policy
• multiple specialist skills need one shared architectural frame

Do Not Stay Here When

• the runtime track is clearly Phaser
• the runtime track is clearly vanilla Three.js
• the runtime track is clearly React Three Fiber
• the task is purely about shipped 3D assets

Once the stack is clear, hand off to the runtime or asset specialist skill.

Architecture Rules

1. Separate simulation from rendering.
   • Simulation owns entities, turns, timers, collisions, progression, and saveable state.
   • The renderer owns scene composition, animation playback, camera, particles, and input plumbing.
2. Keep input mapping explicit.
   • Define actions such as move, confirm, cancel, ability-1, and pause.
   • Map physical inputs to actions in one place.
3. Treat asset loading as a first-class system.
   • Use stable manifest keys.
   • Group by domain: characters, environment, UI, audio, FX.
   • For 3D content, standardize on GLB or glTF 2.0 unless the chosen engine ecosystem requires another format upstream.
4. Define save/debug/perf boundaries up front.
   • Save serializable simulation state, not renderer objects.
   • Keep debug overlays and perf probes easy to toggle.
5. Use DOM overlays for menus and HUD by default.
   • Canvas or WebGL should handle the playfield.
   • DOM should handle text-heavy HUD, menus, settings, and accessibility-sensitive controls.
   • In 3D, keep the persistent UI budget small so the scene stays readable and interactive.
6. Lock 3D runtime conventions early.
   • Choose consistent units, origins, pivots, and naming conventions.
   • Decide how collision proxies, LODs, and baked lighting data are authored before runtime integration starts.

Engine Selection

• Default to Phaser for 2D games with sprites, tilemaps, top-down or side-view action, turn-based grids, and classic browser arcade flows.
• Default to vanilla Three.js for explicit 3D scenes that want direct scene, camera, renderer, and loop control in plain TypeScript or Vite.
• Default to React Three Fiber when the 3D scene lives inside a React application and needs declarative composition, shared app state, or React-first UI coordination.
• Use raw WebGL only for shader-heavy or renderer-first projects where engine abstractions would get in the way.
• Keep Babylon.js and PlayCanvas as alternative-engine paths rather than the default code-generation target.

See ../../references/engine-selection.md for the default decision table.

Implementation Checklist

Define these before writing core code:

• Player fantasy and primary verbs
• Core loop and loss or reset states
• Camera model
• Input action map
• Simulation modules
• Renderer modules
• Asset manifest layout
• 3D asset format and optimization rules
• HUD and menu surfaces
• Save data boundary
• Debug and perf surfaces

Anti-Patterns

• Mixing gameplay rules directly into scene callbacks
• Treating the renderer as the source of truth for game state
• Putting all HUD and menu UI into the canvas by default
• Letting asset filenames become the public API instead of manifest keys
• Shipping unoptimized 3D assets straight from the DCC tool into the browser
• Mixing camera-control state and menu or modal state without an explicit input boundary
• Rebuilding architecture every time the game changes genre

References

• Engine selection: ../../references/engine-selection.md
• Phaser structure: ../../references/phaser-architecture.md
• Three.js structure: ../../references/three-webgl-architecture.md
• Three.js ecosystem stack: ../../references/threejs-stack.md
• React Three Fiber stack: ../../references/react-three-fiber-stack.md
• 3D asset shipping: ../../references/web-3d-asset-pipeline.md