Vendors
HaxeFlixel
HaxeFlixel is an open source 2D game library written for use with the Open Flash Library and the Haxe Toolkit, it is completely free for personal or commercial use. This game library enables multi-platform development for native targets on mobile and desktop as well as Flash and experimental Html5 support on web platforms.
Pygame
Pygame is a set of Python modules designed for writing games. Pygame adds functionality on top of the excellent SDL library. This allows you to create fully featured games and multimedia programs in the python language. Pygame is highly portable and runs on nearly every platform and operating system. Pygame itself has been downloaded millions of times, and has had millions of visits to its website.
Libgdx
ibgdx is a Java game development framework that provides a unified API that works across all supported platforms. The framework provides an environment for rapid prototyping and fast iterations. Instead of deploying to Android/iOS/Javascript after each code change, you can run and debug your game on the desktop, natively. Desktop JVM features like code hotswapping reduce your iteration times considerably.
Umbra
Umbra is on a mission to make it possible to display any 3D content in real time on any piece of hardware. Umbra's solutions are the backbone of a wide range of 3D applications that are used by millions of people every day. Umbra was founded in 2006 and has headquarters in Helsinki, Finland.