December 4, 2012 7:30 AM | Konstantinos Dimopoulos / Gnome
Chris Klimas, the developer of revolutionary choose-your-own-adventure creator Twine, has been working on an open-source, beginner-friendly library for 2D games for Mac, Windows and Linux for quite some time now. Said engine is called Zoetrope and, as you may have already guessed, is already available on the Zoetrope site.
The engine is based on LÖVE and Lua and is not wholly dissimilar to Flixel. What's more, Zoetrope comes with some excellent documentation and one of the easiest to follow scripting tutorials I have ever encountered. Impressively it also supports animated sprites, physics, collision detection, tweens and delayed events, gamepads, saves and levels created in Tiled. Oh, and it's completely and absolutely free; even for commercial projects.