Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/felipeslo/opencode-kit/web-gamesnpx skills add felipeslo/opencode-kit --skill web-gamesgit clone --depth 1 https://github.com/felipeslo/opencode-kitWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00020 | $0.00774 |
| Opus 5 | $0.00010 | $0.00387 |
| Sonnet 5 | $0.00004 | $0.00155 |
| Haiku 4.5 | $0.00002 | $0.00077 |
Grade A, and why
web-games scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
92% identical to web-games — 5 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 150 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Web Browser Game Development
Framework selection and browser-specific principles.
1. Framework Selection
Decision Tree
What type of game?
│
├── 2D Game
│ ├── Full game engine features? → Phaser
│ └── Raw rendering power? → PixiJS
│
├── 3D Game
│ ├── Full engine (physics, XR)? → Babylon.js
│ └── Rendering focused? → Three.js
│
└── Hybrid / Canvas
└── Custom → Raw Canvas/WebGL
Comparison (2025)
| Framework | Type | Best For |
|---|---|---|
| Phaser 4 | 2D | Full game features |
| PixiJS 8 | 2D | Rendering, UI |
| Three.js | 3D | Visualizations, lightweight |
| Babylon.js 7 | 3D | Full engine, XR |
2. WebGPU Adoption
Browser Support (2025)
| Browser | Support |
|---|---|
| Chrome | ✅ Since v113 |
| Edge | ✅ Since v113 |
| Firefox | ✅ Since v131 |
| Safari | ✅ Since 18.0 |
| Total | ~73% global |
Decision
- New projects: Use WebGPU with WebGL fallback
- Legacy support: Start with WebGL
- Feature detection: Check
navigator.gpu
3. Performance Principles
Browser Constraints
| Constraint | Strategy |
|---|---|
| No local file access | Asset bundling, CDN |
| Tab throttling | Pause when hidden |
| Mobile data limits | Compress assets |
| Audio autoplay | Require user interaction |
Optimization Priority
- Asset compression - KTX2, Draco, WebP
- Lazy loading - Load on demand
- Object pooling - Avoid GC
- Draw call batching - Reduce state changes
- Web Workers - Offload heavy computation
4. Asset Strategy
Compression Formats
| Type | Format |
|---|---|
| Textures | KTX2 + Basis Universal |
| Audio | WebM/Opus (fallback: MP3) |
| 3D Models | glTF + Draco/Meshopt |
Loading Strategy
| Phase | Load |
|---|---|
| Startup | Core assets, <2MB |
| Gameplay | Stream on demand |
| Background | Prefetch next level |
5. PWA for Games
Benefits
- Offline play
- Install to home screen
- Full screen mode
- Push notifications
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday First seen · 150 lines · 20 tokens per session scan A 5bd59d080da3
web-games is a skill published in the GitHub repository felipeslo/opencode-kit (2 stars, last pushed 5mo ago), licensed MIT. It adds 20 tokens to every session and 774 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 92% identical to web-games, differing in 5 lines, and is treated as a copy.
Other skills, from other repositories
scale-and-responsive
Use this skill when making a Phaser 4 game responsive or handling display scaling. Covers ScaleManager, scale modes (FIT, RESIZE, EXPAND, ENVELOP), auto-center, fullscreen, and browser resize handling. Triggers on: ScaleManager, responsive, resize, fullscreen, FIT, scale mode.
web-games
Web browser game development principles. Framework selection, WebGPU, optimization, PWA.
html-to-ugui
HTML 原型转 Unity UGUI 智能 Prefab 生成管线。通过 AI 生成符合 UI-DSL 的 HTML，用 Playwright/浏览器烘焙 JSON v2 坐标、图片和适配意图，再导入 Unity 由 HtmlToUGUIBaker 生成可维护、多终端适配的 UGUI Prefab。触发场景：(1) 需要从自然语言生成 Unity UGUI 界面 (2) 需要从 HTML 原型烘焙 UGUI (3) UI 中包含图片并希望一键导入/绑定 Sprite (4) 需要 PC/mobile/pad 多终端适配 Prefab。.
asset-management
Import/export textures crash-safely, query the Content Browser selection, and check if an asset is open (AssetDiscoveryService). Search, load, save, move, rename, duplicate, and delete assets are handled by Unreal's native AssetTools toolset or EditorAssetLibrary. Use when the user asks to import an image from disk…
threejs-gameplay-systems
Build and iterate playable Three.js game systems. Combines starter scaffold creation, architecture, game design, level design, gameplay implementation, combat/encounter design, and game-feel tuning (hitstop, screenshake, easing, impact feedback). Use for first playable slices, new Vite/TypeScript/Three.js game setup…
new-littlejs-game
Scaffold a brand-new, complete playable game project — LittleJS engine included, opens straight from disk in a browser with no server, smallest playable loop written for you. TRIGGER on ANY request to make/create/start/build a game when no other engine or framework is named — "make me a pong game", "make a breakout…