This is an older example of mine, featuring pixel-perfect movement and collision engine for jetpack platformer game. As extras, it includes particle spawning, and impact velocity calculations.
Current version is updated to have a cleaner code style (no more bracket-less conditions and seriously doubtful operator combinations), as long as more comments (increasing comment coverage to a value close to 100%).
Also there was a game being made around this concept once.
Download GMK
Related posts:
the link is broken, upload again please
Fixed.