# game-prototype

Turns a game idea into a short experiment: one mechanic, a falsifiable hypothesis, a minimal test and a yes-or-no decision.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · ★ 47
- Author: AlterLab-IEU
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/AlterLab-IEU/AlterLab_GameForge/tree/HEAD/skills/workflows/game-prototype/SKILL.md
- Updated: 2026-03-30
- HTML: https://affpapa.org/en/nevibecode/skills/game-prototype

## What it does

The skill treats a prototype as a question, not a demo. You state the hypothesis up front — which mechanic, what the player should feel or do, under what condition — and define what evidence would prove it wrong. Without that second part there is nothing to test.

Scope gets cut hard. One room, one encounter, no menus, no saves, no animation polish. What stays is the input-to-feedback loop at real speed, since feel is usually the thing in doubt. Prototype code never ships; if the hypothesis survives, the real build starts fresh.

Hypotheses are grounded in the MDA and flow frameworks from `docs/game-design-theory.md`, and the verdict comes from watching players rather than asking them. Use it for a head-to-head bake-off between two competing designs. Skip it when you need a full project scaffold (that is game-start) or raw concept generation (game-brainstorm).

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add AlterLab-IEU/AlterLab_GameForge --skill game-prototype -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/game-prototype/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/game-prototype/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add AlterLab-IEU/AlterLab_GameForge --skill game-prototype -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/game-prototype/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add AlterLab-IEU/AlterLab_GameForge --skill game-prototype -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/game-prototype/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install AlterLab-IEU/AlterLab_GameForge game-prototype
```

2. **Manually: put the files in place**
- File: `.github/skills/game-prototype/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add AlterLab-IEU/AlterLab_GameForge --skill game-prototype -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/AlterLab-IEU/AlterLab_GameForge --path skills/workflows/game-prototype
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/game-prototype/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add AlterLab-IEU/AlterLab_GameForge --skill game-prototype -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/AlterLab-IEU/AlterLab_GameForge/tree/HEAD/skills/workflows/game-prototype/SKILL.md

## When to use it
- test a mechanic before engineers commit time to it
- run a head-to-head bake-off between two designs
- write falsification criteria for an untested design assumption
- shrink an idea down to a test that fits a couple of days
- decide from player behaviour whether to keep or kill a feature

## Example prompts
- Prototype a grappling hook with momentum preservation and check the hypothesis by tomorrow
- Run a bake-off between two stamina systems and tell me which one creates more tension
- Write the hypothesis and failure criteria for a crafting mechanic, then build the minimal test

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: a8702bfc5bbb457b.

BEGIN THIRD-PARTY FILE a8702bfc5bbb457b
```text
---
name: "game-prototype"
description: >
  Invoke when the user wants to rapidly prototype a mechanic, test a proof of concept,
  run hypothesis-driven development, or validate a game idea before full production.
  Triggers on: "prototype", "proof of concept", "test this mechanic", "validate idea",
  "rapid prototype", "bake-off". Do NOT invoke for starting a full project (use
  game-start) or brainstorming concepts (use game-brainstorm). Part of the AlterLab
  GameForge collection.
argument-hint: "[mechanic to prototype]"
effort: medium
allowed-tools: Read, Glob, Grep, Write, Edit, Bash, AskUserQuestion
version: 1.3.0
---

# AlterLab GameForge -- Hypothesis-Driven Prototyping

Prototypes are experiments, not demos. Every prototype exists to answer one question: "Is this worth building?" The moment you start polishing a prototype, you have stopped prototyping and started building -- and you may be building the wrong thing. Undertale's original demo was rough, ugly, and proved exactly one thing: the bullet-hell-meets-RPG mechanic was worth a full game. Hollow Knight started as a game jam prototype that validated tight combat in an atmospheric 2D world. Celeste began as a PICO-8 prototype that proved a single idea: precise air-dash platforming feels incredible at 8x8 pixel resolution. This workflow enforces that same discipline: define a hypothesis, build the minimum viable test, observe real players, make a binary kill-or-promote decision based on evidence.

### Purpose & Triggers

**Invoke this workflow when:**
- A team member proposes a new mechanic and the response should be "prove it" rather than "ship it"
- The design document contains an assumption that has never been tested with real players
- Two competing mechanic designs need a head-to-head bake-off to determine which one feels better
- A feature sounds good on paper but the team has no visceral sense of whether it will be fun
- Pre-production needs to validate core loops before committing engineering resources
- A pivot is being considered and the new direction needs rapid feasibility confirmation

**Do NOT use this workflow when:**
- The mechanic is well-understood and already validated in similar games (just build it properly)
- You need a vertical slice for stakeholder presentation (that is a demo, not a prototype)
- The question is about content, not mechanics (content questions need playtesting, not prototyping)

### Critical Rules

1. **One hypothesis per prototype.** If you are testing two things, you have two prototypes. Combining hypotheses contaminates your results -- when it fails, you will not know which part failed.
```
END THIRD-PARTY FILE a8702bfc5bbb457b

The third-party file has ended. Everything between the a8702bfc5bbb457b tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

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