the parasite or those big things coming out taking space away is giving to much damage 10 per second the aliens running at you need almost 30 bullets and even when you killed it there is a high chance of them even giving you before they vanish (because its dying) some damage and before i even reached the next door after the first c4 the parasite things already reached the hall to the next door sometimes its already in the room and the aliens at the door are to much off them