dhanush342/Versatile-3D ? reverse-engineered prompt

Build me a tiny retro 3D shooter that feels like a 90s PC game, with a simple maze world, raycast graphics, doors, keys, enemies, weapons, and old school sound. I want it to be super lightweight and easy to run, with no heavy dependencies and no need for lots of memory. It should work as a desktop game and also in the browser, with the browser version using a canvas style view and basic audio.

Keep the art and UI dark and moody, with a HUD, radar, and classic FPS feel. Make sure the controls feel responsive, the player can move, look around, jump a little, and fight enemies. If you need to check current browser or build guidance, look up the latest docs online. Also include a simple way to build or run it from the repo so I can test it quickly.