Aliens: Colonial Marines seeks to create the terror and tension of key moments in the Aliens movie franchise, using high-end graphics and a first-person view to immerse the player. It's DS counterpart, Infestation, just lets you shoot things.
Due out in October, Aliens: Infestation delivers the same movie-reliving experience as its console cousin, only without the constant fear of being torn apart by rampaging xenomoprhs. Here you'll see them coming, and when they arrive you'll be ready with a gun and a number of squad mates backing you up.
For the squeamish, perhaps this is the idea way to relive the Aliens saga. I might swap between the two games to avoid a fear-induced heart attack.