ah...
good game
the nail gun kills all one hit (with a headshot) besides the boss
if you go back to where the med kits are (while fighting the boss) one more rpg will respawn on the right,on your way back and fourth hit him with your chainsaw while jumping
oh yeah i found a bug or glitch...at that part where the turret thingy shoots at you,if you kinda move into the steel door that opens (after you clear all the zombies) you cannot be harmed