Portals (First Person Game)

Portals is a game where people take a gun that makes... Well portals. The point is to get past puzzles that they throw at you. It could be crossing a pit to getting past turrets. The game will ship with HL2 EP2 and TF2 as a package.

Trailer:

http://www.gamespot.com/xbox360/acti...?mode=trailers

More info can probably be found on Valve Software's site.

Portals is actually a professional remake of a Digipen student's indie game called Narbacular Drop. If you want to give it a try, the link is here. Its pretty fun, and seems to give a good indication of what Portals will be like to play.