IGS Labs
Free and Open Game Programming Language for Windows and GNU/Linux
Multi-platform game engine similar to old Megaman with a stage editor
Built to be ease of use, with no programming knowledge, Multi-platform
Advanced 2D/3D(CPU,GPU) Game Engine Library
A complete 2D Game Engine with built in drag and drop editor
A DirectX based graphics/physics engine
Free MMORPG Engine. Develop and host graphical browser-based games.
A simple WinAPI game engine