version: "1.0.1" name: brainstorm-game description: "Turn a vague game idea into a 1-page brief (genre, scope, core loop, mechanics) in .summer/GameSoul.md." license: MIT compatibility: [Cursor, Claude Code, Windsurf, Codex] category: scene-and-project user-invocable: true allowed-tools: Read Grep Glob Write Edit summer_get_project_context summer_get_scene_tree summer_read_file summer_write_file paths: [".summer/", "project.godot", "/*.md"]

/brainstorm-game — Decide What Game to Build

Overview

Most game projects fail because they were never scoped. This skill turns "I want to make a game" into a 1-page brief that names the pitch, the core loop, three mechanics max, the art direction, and the scope (jam / vertical slice / full game). The brief lands at .summer/GameSoul.md — the file Summer's onboarding pipeline and every future Summer skill reads on first turn.

Core principle: Constrain ruthlessly. A buildable bad idea beats an un-buildable great idea. Three mechanics, one art direction, one scope. Anything else gets parked in a "Later" list.

Steps

1. Open with the one question

Ask exactly this and wait:

One sentence — what kind of game do you want to make?

Don't pre-pitch genres. Don't list options. Read what they say. The first sentence is signal.

If they freeze ("I don't know"), offer 4 reference points only:

No worries. Pick the one that pulls you most: a) something cozy and exploratory (Stardew, A Short Hike), b) something tight and skill-based (Celeste, Hades), c) something story-led (Disco Elysium, Citizen Sleeper), d) something silly and short (Goat Sim, Untitled Goose). Or describe a different vibe.

2. Branch on genre signal

Read their answer for a genre anchor and pick one branch. Don't ask multiple questions in parallel.

If unclear, ask the smallest disambiguating question:

Tighter on this — is it more "tense and dangerous" or "calm and exploratory"?

3. Pin the core loop

A core loop is what the player does for 30 seconds, repeated. State a candidate and ask them to refine. Examples per branch:

State your candidate. Ask:

The 30-second loop I'm hearing: <candidate>. Does that match what you have in your head, or is the actual moment-to-moment different?

4. Constrain to three mechanics maximum

Force the trade. State the rule:

Three mechanics, no more. What are the three things this game has that other games in this genre don't?

If they pitch five, push back. Not "we'll add it later" — actually cut. Two examples for them to react to:

Hades has three: dash-attack-cast, room reward choice, and run-end conversation. Everything else (mirror upgrades, weapon variants, bosses) is content built on those three. What are yours?

Common new-dev mistake: listing features ("inventory, crafting, quests") instead of mechanics ("a single resource that's both currency and ammo"). Push them toward verbs and decisions, not nouns and systems.

5. Pick an art direction in one phrase

Not a paragraph. Examples to anchor:

• "Lo-fi PS1 polygons + dithered shader"
• "Hand-drawn 2D, single bold outline, 4-color palette"
• "Toon-shaded Nintendo-bright, no realistic lighting"
• "Pixel art, 16x16 tiles, GameBoy 4-shade green"

Ask:

One phrase for the look. If a stranger asked your screenshot's style in 6 words, what do you say?

Don't go deeper here — /art-direction is where the bible gets built. This is one phrase to seed it.

6. Pin the scope

State the choices flat:

Scope. Pick one: (a) a 4-hour jam-sized prototype — one mechanic, one level, one art direction, ships in a weekend. (b) a vertical slice — 30-60 minutes of polished play that proves the core loop, ships in 2-4 weeks. (c) a full game — 4-20 hours of content, ships in 6+ months.

If they flinch at (c), recommend (b). New devs almost always overestimate scope. Default recommendation if they're unsure: vertical slice.

7. Sanity-check the combination

Do this in your head, not out loud unless something fails:

• Is the core loop achievable with the three mechanics + the chosen art direction in the chosen scope? If not, name what has to flex (usually scope down or merge two mechanics into one).
• Is there a hidden multiplayer requirement? ("4-player" or "co-op" anywhere = stop, multiplayer is its own scope explosion.)
• Is the art direction generatable / sourceable for a solo dev? (Photoreal 3D for a 4-week vertical slice is a red flag.)

If you spot a problem, raise it once, plainly:

One concern: <X>. Suggest <flex Y>. OK or do you want to push through anyway?

8. Draft the brief

Compose the 1-page brief. Format:

# <Game Name or "Untitled">
 
**Pitch:** <One sentence the player would tell a friend.>
 
**Core loop (30s):** <What the player does, repeated.>
 
**Three mechanics:**
1.<Verb-led: "Parry to convert damage into mana"  not "Combat system">
2.<…>
3.<…>
 
**Art direction (one phrase):** <…>
 
**Scope:** <Jam | Vertical slice | Full game>
 
**Win condition:** <How the player knows they succeeded — ending? Score? Unlock?>
 
**One thing this is NOT:** <Define by negation. Cuts scope creep later.>
 
**Inspirations:** <2-4 specific games, films, or images.>
 
**Parked for later:** <Things they pitched that didn't make the three.>

9. Ask permission and write

Preferred (Summer MCP):

May I create .summer/GameSoul.md with this brief?

On yes, use guarded summer_write_file — .summer/GameSoul.md is plain markdown but still belongs to the bound project:

summer_write_file path="res://.summer/GameSoul.md" create_only=true content="<brief>"

If .summer/GameSoul.md already exists, read it first, show what would change, ask:

.summer/GameSoul.md already exists. May I overwrite it, or merge into a "Revision 2" section below the existing brief?

Fallback (Summer MCP unavailable — agent is read-only):

Print the full brief to the user with the explicit instruction:

Save this as .summer/GameSoul.md in your project root. Every Summer skill reads it.

10. Route to the next step

End every successful brainstorm with a routing question:

Brief saved. Next step:

- /design-mechanic — design the core loop in detail (recommended for vertical slice).

- /design-level — sketch level 1 / the tutorial.

- /art-direction — turn the one-phrase look into an art bible.

- Or pick up /make-game to start scaffolding the project.

Don't auto-pick. Let them decide.

Anti-patterns (don't do these)

Collaborative protocol

This skill writes one file (.summer/GameSoul.md). Always ask before writing. Always show the brief inline before saving so the user can react.

Want a working starter?

No template — this is a workflow that produces the brief that drives template selection later. Once .summer/GameSoul.md exists, /make-game reads it and summer list templates shows what's actually available to match against.

See also

• design-mechanic — design the core loop in detail
• design-level — sketch level 1
• art-direction — turn the one-phrase look into a full bible
• audio-direction — sonic identity
• make-game — scaffold the project once the brief is locked

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From a shell

No Summer MCP tools in this session? Run each one as a command; when summer --version is missing or below 4.0, use npx -y summer-engine@latest in place of summer. Fields are flags in kebab-case (--scene-path res://main.tscn) or one --input '<json>', and summer ops describe <op> prints the exact input. The summer-cli skill has the rest.

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