Godot is a powerful cross-platform game engine
Solar2D Game Engine main repository (ex Corona SDK)
The flexible game engine
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
Cocos simplifies game creation and distribution with Cocos Creator
Xash3D FWGS engine
Open source voxel game engine with support for survival and crafting
Multi-platform 2D and 3D game engine
Fast and lightweight JavaScript game engine built on WebGL and glTF
JavaScript-based game engine designed to empower developers
Cross-platform 2D and 3D game engine with modular architecture
V1, Mirror Classic. V2, Mirror Engine: Join Discord for access
Cross-Platform C++ 2D/3D game engine
Game engine supporting many 3D/2D formats and graphic effects
A game engine with an emphasis on real-time cutting-edge solutions
Voxel game-creation platform with easy modding and game creation
The game engine for everyone
GemRB is a portable open-source implementation of the Infinity Engine
An OpenGL RTS game engine written in C
Zig game engine & graphics toolkit
Game engine to build text adventures.
New Godot bindings for Swift
Satisfying monster shooter
A complete 3-D game development suite written in Java
A dead simple 2D game engine for Go