# Brainstorm Game Design > Brainstorm-mode for designing a browser game's CONCEPT before any code — pillars, core loop, player fantasy, mechanics, scope, win/loss. Use when the user wants to design a new game, rethink an existing one, or figure out "what is this game." Facilitates the brainstorm AND writes every accepted decision into game-design/GDD.md in the user's project so no agent (Claude, Cursor, Antigravity) ever l… - **Type:** Skill - **Install:** `agentstack add skill-starchybomb-browser-engine-brainstorm-game-design` - **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior - **Seller:** [StarchyBomb](https://agentstack.voostack.com/s/starchybomb) - **Installs:** 0 - **Category:** [Web & Browser](https://agentstack.voostack.com/c/web-and-browser) - **Latest version:** 0.1.0 - **License:** MIT - **Upstream author:** [StarchyBomb](https://github.com/StarchyBomb) - **Source:** https://github.com/StarchyBomb/browser-engine/tree/main/skills/brainstorm-game-design ## Install ```sh agentstack add skill-starchybomb-browser-engine-brainstorm-game-design ``` Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent. ## About # Brainstorm: Game Design — decide what the game IS, then never lose it This is a design-facilitation mode, not a code mode. Its job is to turn a vague idea ("a shooter, but cool") into a **committed design with pillars and constraints** — and to write that design into the game project so the next session, in any agent, builds the *same* game instead of a new one. **Two failures this mode prevents:** (1) generic design — the game that's a list of features from every other game in its genre; (2) design amnesia — decisions made in chat that vanish, so the next session contradicts them. Both are solved the same way: force real choices, then persist them. ## The persistence contract (non-negotiable — read [../browser-engine/references/design-memory.md](../browser-engine/references/design-memory.md)) Chat proposes; **`game-design/GDD.md` records.** The moment a decision is accepted it is written to the GDD, logged in `decisions.md`, and the summary in `AGENTS.md` is kept in sync so every agent reloads it. A brilliant brainstorm that stays in the transcript is a failure. Scaffold the memory first: [tools/scaffold-design-memory.mjs](tools/scaffold-design-memory.mjs). ## BANNED (generic-design tells — never ship a GDD with these unexamined) - **Genre-by-checklist** — "platformer with double jump, dash, wall-jump, collectibles, boss." That's the genre's feature list, not a design. What's the ONE thing this game does that its genre doesn't? - **No pillars** — a design with no 2–4 pillars can't say no to anything, so it scope-creeps forever. - **Undefined core loop** — if you can't write the 15-second loop the player repeats, there's no game yet, just a setting. - **Fantasy-free mechanics** — mechanics that don't serve a feeling. "You can craft" — to feel like *what*? Master? Survivor? Tinkerer? - **Ignoring the browser** — designing a 200-hour open world for a tab that must load in 5s and run on a phone. Scope to the medium (see [../browser-engine/references/browser-constraints.md](../browser-engine/references/browser-constraints.md)). - **"And also…" scope** — every idea bolted on. A tight game that does one thing brilliantly beats a bloated one that does ten things adequately. - **Deciding art before mechanics** — the look is not the design. Grey-box the fun first. ## Process (facilitate in this order — one question at a time, don't dump a form) 1. **Scaffold the memory** if it doesn't exist — run [tools/scaffold-design-memory.mjs](tools/scaffold-design-memory.mjs) in the game project. Read any existing `game-design/GDD.md` first; you may be continuing, not starting. 2. **Nail the fantasy in one sentence.** "The player feels like ___ doing ___." Everything serves this. If we can't finish it, we brainstorm until we can. 3. **Find the hook** — the one thing this game does that others in its genre don't. A twist on a mechanic, an unusual constraint, a subject nobody's mined. This is what makes it worth building. Pressure-test it: would someone tell a friend about *this specific thing*? 4. **Write 2–4 pillars** — short truths the whole game obeys (e.g. "every death teaches," "no menus, ever," "one screen, no scrolling"). Pillars are how the design says *no*. 5. **Define the core loop** — the 15–60s cycle the player repeats: do X → get Y → spend Y on Z → back to X. If it's not fun in your head as a loop, no art will save it. 6. **List mechanics — and tie each to a pillar/fantasy.** A mechanic with no pillar behind it is a cut candidate. Fewer, deeper mechanics beat more, shallow ones. 7. **Set win/loss/progression** — what ends a run, what carries over, what "getting better" means (skill? unlocks? knowledge?). 8. **Scope to the browser, honestly** — session length, load budget, mobile, solo-dev time. Cut to what ships. Name what's explicitly OUT of scope (the "not-doing" list is as valuable as the doing list). 9. **Critique against the pillars** — walk the whole design back through the pillars and cut anything that doesn't serve one. Then write it all to `GDD.md`, log the session in `decisions.md`, update `AGENTS.md`. 10. **Hand off to build** — the [browser-engine](../browser-engine/SKILL.md) skill and [brainstorm-level-design](../brainstorm-level-design/SKILL.md) now have a source of truth to build from. ## Facilitation style - **One question at a time.** A wall of questions gets a shrug. Ask, react, go deeper, then move on. - **Propose, don't just prompt.** Offer 2–3 concrete options with a recommendation, so the user picks/reacts instead of staring at a blank page. Bring taste. - **Push back.** "That's the generic answer — what if instead…" is the whole value. A yes-man brainstorm produces a yes-man game. - **Converge.** Brainstorm diverges then *commits*. End every session with decisions written down, not a bigger pile of maybes. - **Small scope is a feature.** When in doubt, cut. The best browser games are small and sharp. ## What lands in game-design/GDD.md (the template) Title · one-line pitch · **fantasy** · **hook** · **pillars** (2–4) · **core loop** · **mechanics** (each tied to a pillar) · controls · win/loss/progression · **scope + explicitly out-of-scope** · art/audio direction (last) · open questions. Template: [templates/GDD.md](templates/GDD.md). ## The done check - [ ] Fantasy stated in one sentence; hook is specific and share-worthy - [ ] 2–4 pillars written; every mechanic maps to one - [ ] Core loop written as a concrete 15–60s cycle - [ ] Win/loss/progression defined; scope realistic for the browser + a solo dev - [ ] An explicit out-of-scope list exists - [ ] Everything written to `game-design/GDD.md`; session logged in `decisions.md`; `AGENTS.md` summary in sync - [ ] A fresh agent could read the repo and know exactly what game this is ## Source & license This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code. - **Author:** [StarchyBomb](https://github.com/StarchyBomb) - **Source:** [StarchyBomb/browser-engine](https://github.com/StarchyBomb/browser-engine) - **License:** MIT Install and usage instructions live in the source repository linked above. ## Pricing - **Free** — Free ## Security capabilities Automated source analysis of v0.1.0 — what this tool can access: - **Network access:** no - **Filesystem access:** no - **Shell / process execution:** no - **Environment & secrets:** no - **Dynamic code execution:** no *"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.* ## Versions - **0.1.0** — security scan: passed — Imported from the upstream source. ## Links - Listing page: https://agentstack.voostack.com/l/skill-starchybomb-browser-engine-brainstorm-game-design - Seller: https://agentstack.voostack.com/s/starchybomb - Browse the marketplace: https://agentstack.voostack.com/browse --- Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.