GameSpot announces they will be premiering the demo for Prey on Wednesday June 21 at 9:00 pm Pacific time, which translates to the stroke of midnight Thursday for those of us on the U.S. east coast. Word is the sample of Human Head's DOOM 3-engine first-person shooter will offer one hour of gameplay and will include two multiplayer maps in addition to single-player mode. Further:

Defy the law of nature with gravity flipping, a feature that allows you to walk on ceilings and turns deathmatch mode upside-down. Explore unreachable areas with wall walking, and transport from one sphere to another through space-bending portals. With all these unique gameplay elements, you don't want to miss this highly anticipated FPS demo!