landgreen/n-gon — reverse-engineered prompt

Build me a playable browser game like a 2D physics rogue lite platform shooter. I want it to run from a simple HTML page with JavaScript and CSS, no complicated setup.

The player should be able to move around, jump, aim, and shoot. The world should feel physics based, with platforms, walls, gravity, knockback, and objects or enemies reacting in a satisfying way. Make each run feel a little different, with rooms or levels to fight through, enemies to avoid or destroy, and simple upgrades or powerups that make the player stronger during the run.

Please make it feel like an actual game, not just a demo. Add a start screen, basic controls help, health, score or progress, restart after dying, and some simple visual effects for shooting, hits, and movement. Keep the art clean and lightweight so it works well in the browser. If you need to check current browser game APIs or physics examples, look them up online.