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 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.