Someone posted a thread on /v/, here were my replies.
Enemies have infinite ammo and never ever have to reload ever.
As long as you have 1 health left, you can stand still for about 10 seconds and you'll be completely fine and ready to take another bullet to the face.
Walls do not stop you from running, they just stop you from moving.
Not so much a rule but:
When you're playing a platform type game with lives, you never know if you have 1 or zero lifes left when it says "lives: 1"
Hah, I can definitally relate to the first one. Damn elites on halo2 on legendary edumacate;
That last one pisses me off. Though usually the number refers to extra lives which would mean that once you hit 0, you're on your last shot, but there are exceptions.