Cube 2: Sauerbraten is an open source sequel to Cube by the same company, an FPS with a built in editor. Features include transform and lighting support and fast real-time geometry support. The designers focused more on faster vector processing instead eye candy, to provide a fast, solid gameplay.
There is no story, but a couple campaigns are selectable from the start menu. The soundtrack is thrash metal. The bad guys are generic gun carrying demons and trolls. There are ammo and health packs floating around, similar to Quake 3. You can adjust gravity and even play in slow mode.
The maps provided with the games are similar to Quake and Quake 3.
The game comes with a large arrangement of selectable options, allowing for very customizable gameplay. The sequel comes with rudimentary rag-doll physics, the ability to import Quake 3 models, improved rendering, and easier interface to access and change gameplay.
Like the original game, you can actually change the map using editing tools while playing the game.
Cube 2: Sauerbraten can be seen in a Burger King television commercial from 2006. The commercial shows a guy doing "typical guy stuff" when his girlfriend is out of town. He's neglecting household chores, partying all day long, eating burgers, playing video games and having threesomes.
During the video game part, the guy holds a GameCube controller and gameplay footage of Cube 2: Sauerbraten can be seen briefly. The game was never released on the GameCube, the video editors probably just needed a free game they could show without having to pay royalties.