Metroidvania Ability Gate Game Builder

Build a Metroidvania platformer in one HTML5 file with 3 chained Claude Code prompts. Stage 1: room graph, ability gates, mini-map, gatekeeper. Stage 2: dash, double jump and wall-cling, backtracking shortcuts, save rooms, localStorage save. Stage 3: 3-phase boss, camera, juice, sound, room editor with soft-lock check. Variables: theme, art style, ability set, difficulty, map size. Build videos (4 themes): DASH pickup breaks a gate, double-jump backtrack, 3 rooms, gatekeeper boss beaten.