Please no more Angry Birds type games, it's one of the worst games I've ever played (I'm dead serious).

Many shooter games have traditionally calculated world collision and bullet impacts by modeling bullets as instantaneous line traces and characters as moving collision cylinders. In this case, the line-projecting cylinder is the fundamental nature of the character - the character's substance. The image of a fighter, the sounds he makes and the way he animates is the character's style.

A character can thus be, as a thought exercise, stripped of his style and considered simply as an abstract cylindrical game piece that slides around a level, attempting to project lines into other cylinders.