Command & Conquer: Remastered Collection
Free game engine for development of desktop, mobile, and web games
3D Game engine with editor
Code for Cicero, an AI agent that plays the game of Diplomacy
Source code repository of the FreeOrion project
Descent 3 by Outrage Entertainment
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Vivid3D is a C++ IDE/3D engine, with python scripting.
OgreWin3D
Updated emulator of Forgotten Realms: Unlimited Adventures
Real-time collision detection and multi-physics simulation for VR
3D C++ Game Engine - yet another open source game engine
A 2D game engine and level editor
KlayGE is a cross-platform open source game engine
Retro Games in Gym
Several mods for Civilization IV: Colonization
Karel - 3D language interpreter
EE Keeper is a saved game editor for Baldur's Gate Enhanced Edition.
2D ARPG Engine
Multi-platform game engine similar to old Megaman with a stage editor
evolution for vegastrike SpaceSim/Combat/Trade game
A traditional top-down OpenGL car racing game