Xenko Game Engine
Xenko is an open-source C# game engine designed for the future of gaming.
21 Alternatives To Xenko Game Engine
Amazon Lumberyard
Amazon Lumberyard is a free AAA game engine deeply integrated with AWS and Twitch – with full…

Atomic Game Engine
The Atomic Game Engine features a cross-platform editor with deployment to Windows, OSX, Linux…
Cocos2d-x and Cocos Creator
Cocos Engine Official Website | Cocos Creator | Cocos2d-x | Open Source Cross-Platform Game Development Engine
ENIGMA - LateralGM
ENIGMA, the Extensible Non-Interpreted Game Maker Augmentation, is an open source cross-platform…

Hero Engine
HeroEngine is the only all-in-one development platform for making and operating online games.
Intrinsic
Intrinsic is a Vulkan based cross-platform graphics and game engine.
JMonkeyEngine
What is jMonkeyEngine? It’s a free, open source game engine, made especially for Java game developers who want to create 3D games using modern technology.
MonoGame
MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
Source SDK
The Source SDK is a software development kit compiled by Valve Software that is used to create maps…

Unreal Engine
Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.
WorldForge
The WorldForge project is the original open-source MMORPG project, dating back to 1997.