Purpose This is the concept prototype — a fast, throwaway build that answers one question: "Is this core idea actually fun to interact with?" Default use — run right after and , before writing GDDs or architecture docs. Its verdict determines whether the concept is worth the investment of full design documentation. Mid-production? You can also run this at any stage to test a specific mechanic, design change, or technical question. Pass to activate spike mode: a lightweight 4-hour build with no GDD prerequisites and no phase gate implications. Already have GDDs and architecture complete? To va…