A game-system design tool for one defined milestone, meaning a specific stage or delivery target in development. It creates milestone-scoped design documents and content data, and updates the milestone's progress brief.

Use it to design one game system, document its content and art needs, and record progress for a required milestone.

It keeps system design limited to the work planned for the current milestone instead of expanding into unrelated features.

gat-design — Skill for Codex by Yuki001/game-dev-skills

Install

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.

Any agent

npx skills add Yuki001/game-dev-skills --skill gat-design

Clone the repo

git clone --depth 1 https://github.com/Yuki001/game-dev-skills

Made for: Codex.

Wrote 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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/yuki001/game-dev-skills/gat-design/github.svg)](https://agentmods.dev/skills/yuki001/game-dev-skills/gat-design)

Your own site

<a href="https://agentmods.dev/skills/yuki001/game-dev-skills/gat-design"><img src="https://agentmods.dev/badge/skills/yuki001/game-dev-skills/gat-design/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.

Your own site · 80×15

<a href="https://agentmods.dev/skills/yuki001/game-dev-skills/gat-design"><img src="https://agentmods.dev/badge/skills/yuki001/game-dev-skills/gat-design.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 44 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,283 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin unknown No closer match found in the catalogue.

Token cost

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	$0.00044	$0.02283
Opus 5.5	$0.00018	$0.00913
Sonnet 5.5	$0.00009	$0.00457
Haiku 4.5	$0.00004	$0.00228

Measured 1mo ago against content hash 7ddc27f6d70a, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

gat-design 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 1mo 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.

gat/.agents/skills/gat-design/SKILL.md · 168 lines

The source is not reproduced here

No licence file

Read it on GitHub

Files

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.

agents/openai.yaml 224 B

Changes

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.

1mo ago Changed · +15 lines 7ddc27f6d70a
2mo ago First seen · 153 lines · 44 tokens per session scan A 898c5a359d14

Subscribe to this mod's changes

gat-design is a skill published in the GitHub repository Yuki001/game-dev-skills (108 stars, last pushed yesterday), with no licence file. It adds 44 tokens to every session and 2,283 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.

Game development claude-skills

gat-design next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
gat-designYuki001/game-dev-skills	Skill	108	yesterday	none	A	44	Codex
scenario-blender-retopologyscenario-labs/skills	Skill	3.2k	yesterday	MIT	A	131	Claude Code
scenario-maya-retopology-uvscenario-labs/skills	Skill	3.2k	yesterday	MIT	A	138	Claude Code
scenario-zbrush-expertscenario-labs/skills	Skill	3.2k	yesterday	MIT	A	124	Claude Code
scenario-godot-expertscenario-labs/skills	Skill	3.2k	yesterday	MIT	A	139	Claude Code
scenario-roblox-toolingscenario-labs/skills	Skill	3.2k	yesterday	MIT	A	179	Claude Code
scenario-blender-hairscenario-labs/skills	Skill	3.2k	yesterday	MIT	A	116	Claude Code