http://armorgames.com/play/5395/raze

Raze

Think of this game as a flash version of HALO. in the story mode, you save the humans' alliance, or destroy it, if you choose the alien team, which you can only do when you defeat the human campaign in story mode. In arena mode, you can choose single or team deathmatch, or single/team elimination, in which you all share a certain number of lives, and is you lose them all, you[r team] is out. You get 10 different kinds of weapons:
pistol
bio. uzi
assault rifle
zapper
flame shotgun
sniper rifle
railgun
grenade launcher
ice mini-gun
rocket launcher