Engo is an open-source 2D game engine written in Go
KotCity, an open source city simulator
A cross-platform 2D game engine
The Atomic Game Engine is a multi-platform 2D and 3D engine
online 4X browser game engine
3D .NET engine for Windows, Linux, Mac
plugin-based RPG manager in C++ and Qt5
This is a hacking style game set in the early '80s
Science Fiction, heavy assault, disestablishment of power.
2D physics engine for games
Hungry Hero is an open source Flash game built on Starling Framework.
Cross-platform 2D game engine
Space Exploration Game