Solar2D (successor of Corona SDK)is a free and open-source game engine for Windows, Mac and Linux platforms, originated from the popular and widely utilized Corona SDK game engine, which is no longer receiving commercial support. It utilizes the Lua programming language, and is designed to prioritize simplicity and efficiency in the game development process.

GDevelop is a free, open-source and cross-platform 2D game engine designed to be used by everyone, originally created by Florian Rival (4ian) from United Kingdom in 2008, using C++ and JavaScript. We can use it to create any type of 2D game for Windows, Mac, Linux, iOS and Android platforms, as well as HTML5 Web browsers, Steam platform and Universal Windows Platform.

Godot is a completely free, open-source, cross-platform, and lightweight 2D + 3D game engine. It started as a 2D game engine, but later expanded its capabilities for 3D game development. Compared with many other game engines, it is small in size, rich in features, simpler and easier to use, and more friendly to the novice game makers. The games made with Godot can be simultaneously released to Windows, Mac, Linux, Android, iOS, UWP, and HTML5 platforms.

Door Kickers is a small Real-Time Strategy indie game developed by KillHouse Games (the development team that made the famous module Project Reality for Battlefield 2) from Romania in 2014. It has a lot in common with Frozen Synapse both visually and playfully. However, the user interface and visual effects of the latter are more abstract.

BuildBox is the world's first real sense of foolproof game making tool (founded by Trey Smith in 2014). Because in BuildBox, the entire game development process can be done simply by dragging and dropping operations, no coding, scripting, programming or software design experience required. It's specially developed for entrepreneurs, designers and other game creation enthusiasts without any program development foundation for game design.