Make a small arcade beat 'em up game in one web page: a punk pigeon fighting through a 1990s shopping mall full of rival seagull gangs. Arrow keys move, space attacks. All the art must come from the image model selected for this run: sprite sheets for the hero (idle, walk, kick, hurt), three enemies and a boss, plus a background. Cut the sheets into frames and animate them in the game. Do not draw characters in code. Add a HUD, a score, and win and game over screens. It should feel fun the moment it loads.