isn't Prey on rails? (the iphone version) I'm not sure about this because I have never played it. I know it's touch the enemy to shoot, I just don't know if you move around or if it's on rails.
Yeah, people have already mentioned the two that came to mind...Prey Invasion (not on rails...fun, but short) and Time Crisis (on rails, pretty fun, very short). There's also always Wolfenstein 3D.