they are also bringing out half life 2 for both ps3 and xbox360. Imho that is alot better then halo.
ghost recon
http://www.amazon.com/Clancys-Ghost-...8&s=videogames
Battlefield 2
http://www.amazon.com/Electronic-Art...8&s=videogames
Prey
http://www.amazon.com/2K-Games-71042...8&s=videogames
prey is pretty cool. dl the pc demo first.
Quake 4
http://www.amazon.com/Activision-810...8&s=videogames
Quake 4 is a great game. I have on the PC. it challenging, has a great multiplayer. Theres some slowdown on the 360 version according to reviews though. This game is themost like Halo out of all the ones mentioned.