Aliens: Colonial Marines is a squad-based first-person shooter in which the player controls four Colonial Marines, each with a different personality and primary weapon. Each player character can carry additional weapons including a flamethrower, pulse rifle, smartgun, pistol, RPG, and many types of grenades. The player controls one marine at a time, issues orders to the others using context-sensitive commands, and may switch between characters at any time.
Avoid at all costs, period. I won't even bother listing the reasons why.