The Open Toolkit library is a fast, low-level C# wrapper for OpenGL
Animation Compression Library
Ze Text Adventure game Builder : Create as you play !
Blueshift is a cross-platform 3D game engine implemented in C++
Real-time RPG for PC/tablet/phone; multiple quests and random dungeons
Portable game engine with main focus on point-and-click adventures
Point-and-click 2D game engine