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 merlinhu1/codex-game-studio --skill cgs-vertical-slicegit clone --depth 1 https://github.com/merlinhu1/codex-game-studioWrote 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/merlinhu1/codex-game-studio/cgs-vertical-slice)<a href="https://agentmods.dev/skills/merlinhu1/codex-game-studio/cgs-vertical-slice"><img src="https://agentmods.dev/badge/skills/merlinhu1/codex-game-studio/cgs-vertical-slice/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/merlinhu1/codex-game-studio/cgs-vertical-slice"><img src="https://agentmods.dev/badge/skills/merlinhu1/codex-game-studio/cgs-vertical-slice.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 | $0.00043 | $0.00761 |
| Opus 5 | $0.00022 | $0.00380 |
| Sonnet 5 | $0.00009 | $0.00152 |
| Haiku 4.5 | $0.00004 | $0.00076 |
Grade A, and why
cgs-vertical-slice 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 5d 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.
How it starts
The opening of the file, as written. The whole thing — 89 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Codex Game Studio Vertical Slice
Use this skill for vertical slice work in Template Game.
Objective
Validate whether a full game loop can be built at representative quality before production commitment.
Inputs
- AGENTS.md
- .codex/studio.json
- task-relevant files named by the user or task record
- design/gdd.md
- production/session-state/active.md
- tests/
- .codex/workflows/vertical-slice.md
- docs/architecture/README.md
Arguments
- Objective or user request.
- Target files, scenes, assets, or docs.
- Constraints, deadlines, acceptance criteria, and verification command when known.
Procedure
- Resolve review mode and load concept, systems, architecture, UX, production timeline, and active risks.
- Frame the Validation Question: can a player experience the core fantasy in a representative complete loop, and can the team build that loop at production quality on schedule?
- Apply Scope Discipline: target 3-5 minutes of continuous polished gameplay; cut content before cutting quality; include all systems required for one start-to-challenge-to-resolution loop.
- Plan implementation with explicit systems, quality bar, success criteria, owner roles, and a hard time limit.
- Set a Recovery Checkpoint in production/session-state/active.md so multi-session slice work can resume without guessing.
- Run a Playtest Debrief that captures loop completion, first meaningful action timing, core fantasy, blockers, confusion, and build feasibility.
- Write the verdict as PROCEED / PIVOT / KILL with evidence, risks, and next action.
Write Targets
- tests/
- production/session-state/
- prototypes/
- prototypes/-vertical-slice/
- production/session-state/active.md
Output Contract
- Summary
- Validation Question
- Scope Discipline
- Recovery Checkpoint
- Playtest Debrief
- PROCEED / PIVOT / KILL
- Risks
- Changed files or proposed files
- Verification evidence
- Next owner or decision
Quality Gates
- Validation Question
- Scope Discipline
- Recovery Checkpoint
- Playtest Debrief
- PROCEED / PIVOT / KILL
- Scope remains bounded to the current task and project stage.
- Report labels unverified assumptions separately from evidence.
What ships with it
1 file 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.
- 5d ago First seen · 89 lines · 43 tokens per session scan A 5d0dc5817186
cgs-vertical-slice is a skill published in the GitHub repository merlinhu1/codex-game-studio (53 stars, last pushed 1mo ago), licensed MIT. It adds 43 tokens to every session and 761 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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