RufasGate is a combination of the Portal and Sokoban games. Using stargate terminology, there are Zero Point Modules (ZPMs) that power the portal guns, which in turn create the two ends of a temporary and short range wormhole, a shortcut through space-time, that allows obstacles to be bypassed. In order to empower the portal guns, all cylindrical ZPMs must be bumped onto their base receptacles. There are currently only four levels, and no way to save a game. RufasGate is also a testbed for learning/illustrating various modern OpenGL techniques including cubemaps, water reflections, sound, and glsl shader capabilities. And for anyone planning to use SDL2, it illustrates key-mapping, to get improved keyboard responsiveness from SDL.
Pybik is an interactive, graphical, single player puzzle about the cube invented by Ernő Rubik. Besides the cube, the program can handle towers and bricks (non-cubic puzzles). Pybik also has solvers, pretty patterns, and a collection of various moves. The cube can be manipulated with the mouse or keyboard. You can change the colors or images on the faces of the cube.
OpenXL is a multiple purpose C open engine. It is a proceduralization library. It can be seen as the artist, the designer, or even the programmer of your project. It is designed so that it has some function power that could turn into any task (performing a texture, a pixel art image, a mesh, a model, a level, a song, etc.). The idea is to play the part of the missing components on your team.