CLASSIC ARCADE BENCHMARK 10: Dancefloor Panic. Build a complete playable browser arcade game as one self-contained index.html using Three.js. Create an original dance-arcade-inspired rhythm and reaction score attack practical for keyboard and touch. Use four to six readable fixed positions, incoming prompts, a visible timing line, at least perfect/good/miss judgements, score, local high score, combo, fail/end state, and instant restart. The player must follow prompts in time, build or break combo, choose between a safe and a higher-risk reward route at phrase breaks, and earn or spend a limited focus recovery action. Escalate through pattern structure, route splits, holds, alternation, or announced lane transforms rather than only impossible speed. The game must remain playable through visual beat cues with audio muted; generated sound is optional. Theme, floor design, venue, character presentation, palette, music style, story, and audio are open. No external asset pack. Submit final index.html only, not a mockup or explanation. It must run in a modern browser with no build step.