Desktop/Android/HTML5/iOS Java game development framework
Cross-Platform C++ 2D/3D game engine
3D Procedural Game Engine Using OpenGL
Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D
Doom-based AI research platform for reinforcement learning
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Flax Engine, multi-platform 3D game engine
Powerful, mature open-source cross-platform game engine for Python
Free and open source real-time strategy game
Parabator 2 - Free 3d board game
A work-in-progress PlayStation 4 emulator
FlightGear Flight Simulator: free open-source multiplatform flight sim
3D Engine c++
Odamex is a free, cross-platform, modern client-server Doom engine
0 A.D. is a free, open-source, cross-platform real-time strategy game.
GLScene Engine for Delphi & C++Builder VCL Windows 32/64
GemRB is a portable open-source implementation of the Infinity Engine
WW2 U-boat simulation
Hardcore 3D space shooter with spaceship upgrade possibilities.