Prey puts you in the moccasins of Tommy, your typical unlikely hero who has been wanting to find his way off of the reservation for years. Well, now he has his chance -- only it isn't exactly what he expected. One night, a race of aliens descend upon the earth and scoop up people en masse. Tommy, his girlfriend Jen and his grandfather are all captured and begin being processed by this alien threat. But before the humans can be turned, a band of rebels sabotage Tommy's conveyor belt and he escapes.
Tommy soon watches his own grandfather consumed by the mechanical horrors that the aliens put their victims through and becomes determined to save Jen before she suffers the same fate. But our hero won't have to go it alone, as soon his grandfather goes Obi-Wan Kenobi and starts appearing to our hero in ghostly visions.
Now Tommy cannot only wield the various weapons of the alien invaders, but he also has an ancient ability called Spirit Walking. With this ability, Tommy can leave his body and move through force fields and activate switches. He also has a spirit bow that uses spirit energy (which rebuilds over time) and allows you to sneak up on enemies.
With the exception of the Spirit Walk stuff, Prey doesn't really sound like anything special, right? Where the innovation really kicks in is with the game's loose definition of gravity and its extensive use of portals.
First the gravity. It seems this invading race has developed walkways that allow you to not only walk up walls, but also along ceilings. This means that you will really have to keep your wits about you when you walk into a new room. Don't just look at eye level or at the platforms above and below you, keep an eye out on the walls and ceilings.
This also means it is really easy to get turned around. There were a couple of occasions where I had walked onto the ceiling and some enemies spawned on the floor I had just left. As I dodged and backed away from their fire, I inadvertently walked back onto the floor with my back to them -- not a good idea.
The other major feature of the game are portals and one-way doors that are scattered throughout the alien ship. Early on, you see plenty of good examples of these doorways. One of the coolest parts in the game is when you walk into a room with nothing but a portal and a glass case holding a small brown sphere. When you walk into the doorway, you find yourself transported onto the sphere (and shrunken to fit onto it) and see enemies come into the room, look at you in the case, and come after you through their own portals. Unfortunately, this happens pretty early on and it is, at least in my opinion, the best use of the mechanic. Essentially, the game shows its hand early on and never really tries to do anything better.
There is one final aspect that keeps this game from being just another FPS. About halfway through the game, you get access to vehicles that float around. This is used to solve a few puzzles and kill some of the larger enemies. Frankly, I felt like this whole aspect could have been left out. It feels tacked on, and never feels quite intuitive enough to get used to. To make matters worse, the last quarter of the game uses these shuttles almost exclusively, making it a real headache.
Prey also has two multiplayer modes, Deathmatch and Team Death Match. There isn't anything real special about these modes. They are your standard run-and-gun, frag-counting modes and anyone who has played one of the many other Deathmatch games out there will be able to pick up these mods without any problems.