Товарищи, Diamond Fighters is a tank arcade game that can be played alone or in two-player mode against computer-controlled enemies in a progression-based level system. I find it quite fun (it has upgrades & destroyable walls!) and good-looking (yay for pretty explosions!). Its source code is GPLed (no idea about art.)
iamar [home page, project page] is a project for teaching students how to make 3d games. It covers 3D modelling in blender and 3D game programming. The project consists of video material and the "iamar browser" which uses an in-house scripting engine called "semblis".
I have not tried to run it yet, but it is rather relevant to my interests, even though the "we made our own scripting language" deal does sound rather lame.
Geek game news time! MyMan (yo!) is a Pac-Man clone for the command line interface. Despite being a text-mode game, it doesn't look like crap! No horrible Nethack-like symbol clutter! (Yes, you're reading the words of an ASCII-hater right now! :P) It also supposedly has sound, although I have not tried to build it with it enabled.