Paladin is a Mozilla project to push 3D gaming on the Web. It’s intended to allow games to be deployed entirely in the browser, with no plugins required. Multiple platforms and devices, including mobile tablets and phones, can be targeted with a single code base, and no compiling is required during development. For production releases, assets can be bundled with the game or fetched dynamically from the web at runtime. Paladin is currently comprised of several related project. Gladius, the game engine, a joystick API for Firefox and a mouse lock API for Firefox.
More at Mozilla Labs.