Via Offworld we notice that 2D Boy have released a "not-revolutionary" Rapid Prototyping Framework, to help other would-be devs on their way. This gives you a trimmed down version of the tools 2D Boy used to make World Of Goo. 2D Boy explain:
This means two things:
1. Minimizing the amount of code required to set up a new game
2. Providing all the basic facilities so as to avoid wasting time reinventing the wheel (2D rendering, sound, input, persistence layer, and resource management)
Which is probably quite neat, if you're wanting to make a 2D game from scratch.