OgreWin3D
Voxel game engine in C++ with OpenGL
Cross-Platform C++ 2D/3D game engine
Free game engine for development of desktop, mobile, and web games
A fast and reliable entity component system (ECS) and much more
A shield for the Arduino Mega that can back up video game cartridges
An Open Source DOS emulator to run old DOS games
3D Engine c++
FlightGear Flight Simulator: free open-source multiplatform flight sim
4X Space Strategy Game
Good-looking and addictive OpenSource games
A planetarium software that shows a 3D simulation of the night sky
C64/Amiga emulator with shader and runAhead
Multiplatform MIDI File Player for Linux, Windows, and macOS
WW2 U-boat simulation
Cooperative multiplayer graphical RPG and adventure game