About two weeks ago, I wrote an article on how the player input is handled in Smash Battle. It basically tells what the GameInput class does and how to use it. It might be useful if you're working on a C++/SDL project, or just to get an insight in how Smash Battle handles its input.

EDIT: Smash Battle has also been featured on two sites, the Linux Game Tome and Pixel Prospector, which is a site that collects quality freeware games. We're honored! :)