Build a playable Super Mario Bros-style 2D platformer in the browser, recreating World 1-1. Single page, no external assets: draw every sprite, tile and background with code. Run and jump with variable jump height, smooth side-scrolling camera, question blocks that pop coins and a mushroom power-up, breakable bricks, Goombas you can stomp, pipes, pits, and a flagpole finish. HUD with score, coins, world and timer, plus title and game-over screens. It should feel tight and fun the moment it loads.