I gave up on the game some where around the part where polar bears were shooting at me. By the way, this game is highly unimaginative and boring.
p.s. why do all the guns use the same ammo?
The boss isn't that hard. When he starts to spray bullets every where stay directly to the left of him (he should have a blind spot there) and track him. For the rest of the time avoid his shots and stuff. Easy