Godot is a powerful cross-platform game engine
Cocos simplifies game creation and distribution with Cocos Creator
Fast and lightweight JavaScript game engine built on WebGL and glTF
Flax Engine, multi-platform 3D game engine
Cross-platform 2D and 3D game engine with modular architecture
Xash3D FWGS engine
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Cross-Platform C++ 2D/3D game engine
The flexible game engine
Multi-platform 2D and 3D game engine
Zig game engine & graphics toolkit
Solar2D Game Engine main repository (ex Corona SDK)
An OpenGL RTS game engine written in C
A game engine with an emphasis on real-time cutting-edge solutions
Open-source engine for Heroes of Might and Magic III
A grid based movement engine compatible with Phaser3
A modern cross-platform low-level graphics library
GZDoom is a feature centric port for all Doom engine games
LayaAir is an open-source 2D/3D engine
UCI chess engine
Unreal Engine Archives Explorer
Open source voxel game engine with support for survival and crafting
A complete 3-D game development suite written in Java
A Minecraft mod designed to improve frame rates
A modular Common Lisp game engine