| name | gat-design |
| description | Run the full design pipeline with brainstorm wizard, or add one missing system. |
| argument-hint | [<hint> | <system-name>] |
| user-invocable | true |
| allowed-tools | Read, Glob, Grep, Write, Edit, Agent, AskUserQuestion |
Design
This skill writes all design and art documents.
Phase 1: Resolve Mode
Check existing files:
- If
design/gdd/game.md missing → Mode: wizard
- If argument matches a system name in
systems-index.md → Mode: system
- If
game.md exists and at least one system in systems-index.md lacks a GDD → Mode: continue
- If
game.md exists and all systems have GDDs → report design is complete, stop
Treat any non-system-name argument as a concept hint passed into the wizard.
Phase 2: Wizard
Skip this phase if Mode is continue or system.
Step 1 — Core Concept
If a concept hint was provided, first spawn gat-designer to extract what is already answered from the hint:
- genre / style
- core player verb
- target feeling
- rough scope
Then use AskUserQuestion to ask only the questions the hint did not answer. If the hint answered all four, skip Step 1 entirely and proceed to Step 2.
Step 2 — Concept Direction
Spawn gat-designer to generate 2-3 short concept directions (3-5 sentences each) based on Step 1 answers.
Use AskUserQuestion:
- "Which direction resonates most, or describe your own?"
- Options: present the 2-3 directions as options plus "Describe my own"
Step 3 — System Scope
Spawn gat-designer to propose a system list with brief rationale for each, based on the chosen direction.
Use AskUserQuestion (multiSelect):
- "Which systems should be in scope?"
- List the proposed systems as options
Then use a second AskUserQuestion:
- "Any systems to add that are missing? (leave blank to continue)"
Step 4 — Confirm Before Writing
Show a one-paragraph summary: chosen direction + confirmed system list.
Use AskUserQuestion:
- "Ready to write the design docs?"
- Options:
Yes, write them (Recommended) / Let me adjust something
If user wants to adjust, loop back to the relevant step.
Phase 3: Execute
Read templates:
.claude/docs/templates/design/game-overview.md
.claude/docs/templates/design/systems-index.md
.claude/docs/templates/design/system-gdd.md
.claude/docs/templates/design/global-art.md
.claude/docs/templates/design/system-art.md
.claude/docs/templates/design/content-data.md
Wizard or Continue mode
If Mode is wizard: execute Steps 1-5 below in order.
If Mode is continue: skip Steps 1-2, go directly to Step 3.
Step 1 — Spawn gat-designer to write design/gdd/game.md and design/gdd/systems-index.md:
- Pass wizard answers (direction, confirmed system list)
- Pass templates
- Instruction: write both files in one pass
Step 2 — Spawn gat-artist to write design/art/art-direction.md:
- Pass
game.md, global-art template
- Pass existing
art-direction.md if present
Ask after Step 2 complete - After step 2 complete, Let user confirm changes:
Use AskUserQuestion:
- "Do you want to change the design docs? Or continue to next step?"
- Options:
Yes, continue to next step / Let me adjust something
Step 3 — For each system in systems-index.md lacking a GDD, in order:
Spawn gat-designer → design/gdd/<system>.md:
- Pass
game.md, systems-index.md, system-gdd template
- Pass existing system GDD if present
Step 4 — Content Fill (for systems with high content volume)
For each system whose system GDD is complete AND which requires substantial content data, spawn gat-designer to write design/content/<system>-data.md:
- Pass the system GDD,
game.md, systems-index.md, content-data template
- Pass existing content doc if present
- The content doc fills specific instances, parameters, sequences, and groups — the data that instantiates the rules defined in the system GDD
A system needs a content-data doc when its GDD defines data structures that need many concrete instances (e.g. an enemy GDD defines enemy attributes → content doc fills 25+ specific enemies; a stage GDD defines wave scheduling → content doc fills wave-by-wave scripts for all 5 stages).
Systems that are purely mechanical (e.g. input, tbs-scoring) typically do NOT need content-data docs — their parameters fit within the GDD itself.
Step 5 — For each system in systems-index.md lacking an art doc, in order:
Spawn gat-artist → design/art/<system>-art.md:
- Pass
game.md, art-direction.md, the system GDD, the content-data doc (if it exists), system-art template
- Pass existing system art doc if present
- The artist now has both the GDD (rules/schema) and the content-data doc (specific instances) to design complete visuals
System mode
Require design/gdd/game.md and design/gdd/systems-index.md.
Step 1 — Spawn gat-designer → design/gdd/<system>.md
Step 2 — If the system needs content data, spawn gat-designer → design/content/<system>-data.md
Step 3 — Spawn gat-artist → design/art/<system>-art.md (pass GDD + content-data if exists)
Phase 4: Review
Summarize what was created or updated.
Use AskUserQuestion:
Plan milestones (Recommended) → Run /gat-milestone
Add another system → Run /gat-design <name>
Stop here