The flexible game engine
Godot is a powerful cross-platform game engine
Solar2D Game Engine main repository (ex Corona SDK)
An OpenGL RTS game engine written in C
Multi-platform 2D and 3D game engine
Cross-platform 2D and 3D game engine with modular architecture
Fast and lightweight JavaScript game engine built on WebGL and glTF
Cross-Platform C++ 2D/3D game engine
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
JavaScript-based game engine designed to empower developers
Cocos simplifies game creation and distribution with Cocos Creator
A game engine with an emphasis on real-time cutting-edge solutions
A game engine powered by python and panda3d
Flax Engine, multi-platform 3D game engine
V1, Mirror Classic. V2, Mirror Engine: Join Discord for access
Xash3D FWGS engine
The Ren'Py Visual Novel Engine
A retro game engine for Python
Zig game engine & graphics toolkit
Powerful, mature open-source cross-platform game engine for Python
Open source voxel game engine with support for survival and crafting
A complete 3-D game development suite written in Java
Open source clone of the Age of Empires II engine
GemRB is a portable open-source implementation of the Infinity Engine
Game engine supporting many 3D/2D formats and graphic effects