Great Xbox 360 Games

Xbox 360 great games?

Hi, I am look for some good xbox 360 games.
These games i have:
COD: WAW
COD: 4
Oblivion: elder scrolls IV
Guitar Hero 3: legends of rock
I am look for some good online games, and games for splitscreen, like for against friends at your house.
Also in Unreal tournament 3 a good game?

Unreal Tournament is okay.

Other good games:

Gears of War 2: Great online play. Has coop and split screen online. It is the biggest game for the 360 so far. Great guns like the lancer which is a machine gun with a chainsaw on it. (3rd person)

Left 4 Dead: Four single player stories. Coop, offline and online. One “Best Multiplayer mode” which is Zombies vs Humans. Humans try to make it to the evacuation point, will the zombie players have to infect them with brutal cannibal moves. (1st person)

E3 2011: Microsoft Xbox 360 Kinect Games Highlights