Open 3D Engine (O3DE) is an Apache 2.0-licensed multi-platform 3D
Powerful, mature open-source cross-platform game engine for Python
Self-hosted game stream host for Moonlight
Cocos simplifies game creation and distribution with Cocos Creator
Cross-Platform C++ 2D/3D game engine
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Flax Engine, multi-platform 3D game engine
Cross-platform 2D and 3D game engine with modular architecture
3D Procedural Game Engine Using OpenGL
Map Pixel Art Generator for Minecraft
Free game engine for development of desktop, mobile, and web games
Voxel game engine in C++ with OpenGL
Open source clone of the Age of Empires II engine
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
3D game engine with lua scripting
Multi-platform 2D and 3D game engine
3D Game engine with editor
Voxel game-creation platform with easy modding and game creation
Desktop/Android/HTML5/iOS Java game development framework
Free and open source real-time strategy game
A free/open source client and automation tool for Ragnarok Online
Code for Cicero, an AI agent that plays the game of Diplomacy
Source code repository of the FreeOrion project
GemRB is a portable open-source implementation of the Infinity Engine
Vivid3D is a C++ IDE/3D engine, with python scripting.