N (as in Ninja) from Metanet Software is the best (flash) game ever made…the simplicity of design and gameplay bubbles up into a fabulously dynamic experience…seriously, check it out. Plus the website has a bunch of great tutorials on some pretty advanced collision detection techniques.
from the website:
N has been described as reminiscent of lode runner — you're a little dude running around in a puzzle-y world inhabited by enemies.
But in N, there's a twist: the ninja is driven not only by a thirst for gold, but also by a physics simulation.
Death, which happens often, is quite animated.