Cards on the table, I've never played Prey. It was 2006, and I wasn't that into my PC gaming (or gaming overall) as much as I am now. I was away of it at release though, dismissing it as yet another FPS where you'd be trying to kill something for some contrived reasons.
Prey is not that simple though. It actually tells the tale of a Native American man who is abducted, along with his girlfriend and grandfather, into a semi-organic alien spaceship called The Sphere, and the fight back against the cybernetically enhanced alien races that maintain the invading ship.