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
Xash3D FWGS engine
Multi-platform 2D and 3D game engine
Cocos simplifies game creation and distribution with Cocos Creator
Open source voxel game engine with support for survival and crafting
Fast and lightweight JavaScript game engine built on WebGL and glTF
Native Android app for Habitica
An unofficial rules engine for the world's greatest card game
Cross-platform 2D and 3D game engine with modular architecture
Voxel game-creation platform with easy modding and game creation
Unicorn CPU emulator framework (ARM, AArch64, M68K, Mips, Sparc
Game engine supporting many 3D/2D formats and graphic effects
The game engine for everyone
A game engine with an emphasis on real-time cutting-edge solutions
Zig game engine & graphics toolkit
Satisfying monster shooter
GemRB is a portable open-source implementation of the Infinity Engine
An OpenGL RTS game engine written in C
Motor de juegos de aventura programable
New Godot bindings for Swift
A dead simple 2D game engine for Go
Open source routing engine for OpenStreetMap