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 skills add seaworld008/Commonly-used-high-value-skills --skill develop-web-gamegit clone --depth 1 https://github.com/seaworld008/Commonly-used-high-value-skillsWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/seaworld008/commonly-used-high-value-skills/develop-web-game)<a href="https://agentmods.dev/skills/seaworld008/commonly-used-high-value-skills/develop-web-game"><img src="https://agentmods.dev/badge/skills/seaworld008/commonly-used-high-value-skills/develop-web-game/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/seaworld008/commonly-used-high-value-skills/develop-web-game"><img src="https://agentmods.dev/badge/skills/seaworld008/commonly-used-high-value-skills/develop-web-game.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What 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 5.1 | $0.00029 | $0.02142 |
| Opus 5 | $0.00015 | $0.01071 |
| Sonnet 5 | $0.00006 | $0.00428 |
| Haiku 4.5 | $0.00003 | $0.00214 |
Grade A, and why
develop-web-game scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
88% identical to develop-web-game — 28 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 159 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Develop Web Game
Build games in small steps and validate every change. Treat each iteration as: implement → act → pause → observe → adjust.
Skill paths (set once)
export CODEX_HOME="${CODEX_HOME:-$HOME/.codex}"
export WEB_GAME_CLIENT="$CODEX_HOME/skills/develop-web-game/scripts/web_game_playwright_client.js"
export WEB_GAME_ACTIONS="$CODEX_HOME/skills/develop-web-game/references/action_payloads.json"
User-scoped skills install under $CODEX_HOME/skills (default: ~/.codex/skills).
Workflow
- Pick a goal. Define a single feature or behavior to implement.
- Implement small. Make the smallest change that moves the game forward.
- Ensure integration points. Provide a single canvas and
window.render_game_to_textso the test loop can read state. - Add
window.advanceTime(ms). Strongly prefer a deterministic step hook so the Playwright script can advance frames reliably; without it, automated tests can be flaky. - Initialize progress.md. If
progress.mdexists, read it first and confirm the original user prompt is recorded at the top (prefix withOriginal prompt:). Also note any TODOs and suggestions left by the previous agent. If missing, create it and writeOriginal prompt: <prompt>at the top before appending updates. - Verify Playwright availability. Ensure
playwrightis available (local dependency or global install). If unsure, checknpxfirst. - Run the Playwright test script. You must run
$WEB_GAME_CLIENTafter each meaningful change; do not invent a new client unless required. - Use the payload reference. Base actions on
$WEB_GAME_ACTIONSto avoid guessing keys. - Inspect state. Capture screenshots and text state after each burst.
- Inspect screenshots. Open the latest screenshot, verify expected visuals, fix any issues, and rerun the script. Repeat until correct.
- Verify controls and state (multi-step focus). Exhaustively exercise all important interactions. For each, think through the full multi-step sequence it implies (cause → intermediate states → outcome) and verify the entire chain works end-to-end. Confirm
render_game_to_textreflects the same state shown on screen. If anything is off, fix and rerun. Examples of important interactions: move, jump, shoot/attack, interact/use, select/confirm/cancel in menus, pause/resume, restart, and any special abilities or puzzle actions defined by the request. Multi-step examples: shooting an enemy should reduce its health; when health reaches 0 it should disappear and update the score; collecting a key should unlock a door and allow level progression. - Check errors. Review console errors and fix the first new issue before continuing.
- Reset between scenarios. Avoid cross-test state when validating distinct features.
- Iterate with small deltas. Change one variable at a time (frames, inputs, timing, positions), then repeat steps 7–13 until stable.
What ships with it
6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 3d ago Changed · -35 tokens per session 4bdf0629d8b4
- 11d ago First seen · 159 lines · 64 tokens per session scan A eecd17a801d2
develop-web-game is a skill published in the GitHub repository seaworld008/Commonly-used-high-value-skills (70 stars, last pushed 3d ago), licensed MIT. It adds 29 tokens to every session and 2,142 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 88% identical to develop-web-game, differing in 28 lines, and is treated as a copy.
Other skills, from other repositories
develop-web-game
Use when Codex is building or iterating on a web game (HTML/JS) and needs a reliable development + testing loop: implement small changes, run a Playwright-based test script with short input bursts and intentional pauses, inspect screenshots/text, and review console errors with rendergametotext.
test-reporting
Run the Level 2 dummy agent integration test suite and produce a detailed HTML report with per-test input → outcome analysis.
multi-agent-e2e-validation
Multi-agent parallel E2E validation for database refactors. TRIGGERS - E2E validation, schema migration testing, database refactor validation.
symmetric-dogfooding
Bidirectional integration validation where two repositories validate each other before release.
schema-e2e-validation
Earthly E2E validation for YAML schema contracts. TRIGGERS - schema validation, YAML schema, schema contracts, regenerate types.
browser-qa-delivery
Validate a Design Studio HTML artifact in the sandbox browser, fix rendering and runtime defects, then deliver exactly the tested file.