Open source clone of the Age of Empires II engine
A retro game engine for Python
The Ren'Py Visual Novel Engine
Vivid3D is a C++ IDE/3D engine, with python scripting.
A cell-based puzzle game featuring classic and completely new puzzles
PyCAPGE - Python Classic Adventure Point and Click Game Engine
Tactical, turn-based game engine, that uses OpenGL and WinAPI