prototype

Define a falsifiable hypothesis about the core mechanic, choose a prototype path (HTML, engine, or paper) based on your genre, build a minimal throwaway version testing one mechanic, then run a playtest debrief. The result is a PROCEED, PIVOT, or KILL verdict with a written report.

Use the Engine path for action, platformer, or physics games where feel is the hypothesis. Use HTML for puzzle, idle, or turn-based logic games. Use Paper for strategy, card, economy, or narrative games where rules matter more than feel.

No. Browsers introduce 50-133ms of rendering variance, which makes HTML prototypes unreliable for action games, platformers, or anything where input timing and collision feel are being tested. Use a native engine prototype for feel validation.

Spike mode is a lightweight ~4-hour prototype for mid-production questions, triggered with the --spike flag. It tests a specific mechanic or technical approach without GDD prerequisites or phase-gate implications, producing a short SPIKE-NOTE.md instead of a full report.

The Skill captures a PIVOT-NOTE.md recording what worked, what to change, and a revised hypothesis for the next prototype. After three PIVOT iterations on the same concept, it forces a KILL decision to avoid the sunk cost trap.

No. Prototype code must never be imported into production, and production code must never be imported into prototypes. If the verdict is PROCEED, the production implementation is written from scratch.