MonoGame
MonoGame is an open source implementation of the Microsoft XNA 4 Framework.
21 Alternatives To MonoGame
Adventure Game Studio
Adventure Game Studio provides the tools to make your own adventure, for free!
Armory3D
Armory 3D is a free and open source game development software developed using Haxe and Kha and made to run inside Blender.
Blacksmith 2D
Black is a highly optimized 2D framework for web, mobile games, and playable ads.
Cocos2d-x and Cocos Creator
Cocos Engine Official Website | Cocos Creator | Cocos2d-x | Open Source Cross-Platform Game Development Engine
Construct 2
Scirra Construct is a 2D game development engine with a focus on building games visually.
FlatRedBall
Cross-platofrm 2D game engine using C#, focused on developer productivity, transparency, scalability, and ease of use.
LITIengine
LITIengine is a free and open source Java 2D Game Engine. It provides all the infrastructure to create tile based 2D games with plain java, be it a platformer or a top-down adventure.
RPG Maker
Make your own PC game with RPG Maker. Our easy to use tools are simple enough for a child, and powerful enough for a developer. Try it free today!
Unity3D
Unity is the ultimate game development platform. Use Unity to build high-quality 3D and 2D games, deploy them across mobile, desktop, VR/AR, consoles or the Web, and connect with loyal and enthusiastic players and customers.
Unreal Engine
Unreal Engine 4 is a suite of integrated tools for game developers to design and build games, simulations, and visualizations.