Vivid3D is a C++ IDE/3D engine, with python scripting.
A 2D game engine and level editor
Build Cross-platform Applications
Vivid Engine 2 is an open source 3D Engine coded using C# and C++.
IRB is a game creation toolkit
2D game engine for traditional platform games
Open Game Bootstrap
Single-/multi-player card game Mau Mau (similar to UNO®)