Engines
Here’s a list of interesting engines :
Vortex2d
Vortex2D.NET is free 2D fast graphics framework/game engine powered by Direct3D 9. It is replacement of XNA for 2D games development. Vortex2D API is very well structured, easy for beginners and powerful for professionals. Programming language: C#; OS: Win XP or newer.
Stencyl
Stencyl makes it easy to create and share fun flash games in a matter of hours.
Impact
Impact is a JavaScript Game Engine that allows you to develop HTML5 Games in no time. Games created with Impact require no browser plugins or any software installations – just a modern browser that supports the Canvas tag.
Flashpunk
FlashPunk is a free ActionScript 3 library designed for developing 2D Flash games. It provides you with a fast, clean framework to prototype and develop your games in. This means that most of the dirty work (timestep, animation, input, and collision to name a few) is already coded for you and ready to go, giving you more time and energy to concentrate on the design and testing of your game.
LibGDX – a cross-platform 2D and 3D game development framework written in Java/C/C++.
LÖVE
is an *awesome* framework you can use to make 2D games in Lua. It’s free, open-source, and works on Windows, Mac OS X and Linux.