Dead Space: Extraction

You'll unlock the Life Support Room Challenge after completing Chapter 10 of the story mode. The top score is 260,010 so you need more than this to earn the trophy.

This level is a strange one because it is done in zero gravity. Because of this, the type of enemies you'll be facing are just two, the ones that crawl along the floor and attack you with their tail and the little baby ones with tentacles that fire at you. What this means is that you'll be able to use the tactic from Overtime Sheet, but you'll also need to be ready with the Rivet Gun as the baby necromorphs never get close enough to be able to get shot at with the Flame-Thrower. One thing to note is that at the end of each round you'll have to jump to the next ledge before the next round starts, which means you'll be able to reload all your weapons and pick up all the ammo before you do this. I got a streak of 52 and that gave me 280,591 points. There are not so many enemies in this round so you'll want to aim for as big a streak as you can. 80+ is good.