i would think that having a battle suit would enable me fire proof[/quote]
Actually, although metals take far longer to heat up than flesh, they also lose their heat just as slowly. So, in a sense, self-damage should rise very slowly but last for several minutes at least.
But in a game with instantaneously evolving aliens, with perpetually running jetpacks, with humans who build things with a gun-shaped notepad, what does reality matter? This isn't the kind of game where we take reality into consideration. In games like Counter-Strike or Call of Duty, reality matter (usually), but in a sci-fi, alien shoot-em-up game, fun-ness rules over feasibility.