Godot is a powerful cross-platform game engine
Solar2D Game Engine main repository (ex Corona SDK)
Multi-platform Engine for Desktop, XBOX (UWP) and Mobile games
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
A JavaScript engine optimized for running React Native
Xash3D FWGS engine
Game engine supporting many 3D/2D formats and graphic effects
Use the Delta Executor APK with Roblox on a Windows PC.
Satisfying monster shooter
The game engine for everyone
Voxel game-creation platform with easy modding and game creation
An unofficial rules engine for the world's greatest card game
GemRB is a portable open-source implementation of the Infinity Engine
A dead simple 2D game engine for Go
New Godot bindings for Swift
Sandbox video game with a powerful physics engine
Open-source engine for Heroes of Might and Magic III
A completely free, open-source, 2D game engine
scene-oriented, flexible 3D engine (C++, Python, C#, Java)
Java/JavaFX/Kotlin Game Library (Engine)
Free, cross-platform 2D game engine powered by Haxe and OpenFL
KorGE Game Engine. Multiplatform Kotlin Game Engine & Korlibs
An open source C++ game engine