My most played Xbox 360 games are the first Rainbow Six Vegas, Call of Duty 4, and Marvel: Ultimate Alliance.

360 game? Probably Rockband. CoD4 is up there too although i don't play that much anymore. But i always go back to Rockband.

This is still hard for me to believe, but mine is Crackdown.  It is not my favorite game, but I spent way too much time collecting those orbs.

On my 360, I've definitely played Rock Band the most. Close behind that is Oblivion.

Overtime, it'd be Gears of war. I played that game forever. I haven't played it in over a year, because all the updates messed the game up.

The game that I have played most is Halo 3, followed closely by Gears of War.

Played Rainbow Six Vegas for so damn long, and tons of Call of Duty 4.

Call of Duty 4 or Halo 3.

GTAIV

Rock Band and Forza 2

Burnout Paradise

Definitely Rock Band. Going through all those solo careers and BWT took a loooong time.

Oblivion, by far.. played through the whole thing twice, plus shivering isles... probably bout 250 hours all said.

RSV2 or CoD4

Halo 3. Beat capaign two and a half times. Got all skulls. Played over 1300 games. Halo 3.

Gears of War. Beat campaign on all difficulties at least 3 times. Yes, that does include Insane.

thats tough... probably Gears. beat it a couple times. Spent a LONG time playing online.

Not real sure, it's going between Halo 3, Marathon and Doom.

Gears of War. So many hours spent playing the multiplayer.

GRAW 2

Call of Duty 4. I have spent so many hours playing multiplayer. Oblivion would be my second most played 360 game.

oblivion, and then probably nba 2k8

Day of Defeat.

Rock band or halo 3

tacked in 500+ hours in forza 2.
200+ in gta IV [before it broke]

Whenever I'm waiting for the next game to arrive from Gamefly I find myself more times than not popping in good ol' Rock Band. Rock on!

Probebly Gears of War, then Halo 3 or COD 4 second, StarCraft must be my Nr1. Played game of all time tho.

The longest game I ever played was Final Fantasy XI with over 1,600 hours. I have no idea how much I played Counter-Strike, but Super Smash Bros. Melee is likely my second most played with over 100 hours.

For 360:
1.  Halo 3
2.  Gears of War
3.  Call of Duty 4

Just guessing best I can I'd say it would have to be Oblivion, love Elder Scrolls series.

Some games up there would be Oblivion, Two Worlds, Mass Effect, Halo 2/3 and COD4...

On the 360, probably Oblivion or Call of Duty 4

Either Call of Duty 4 or GTA4

Gears of War, Halo 3 I don't really know for sure

1. Halo 3

Gears of war

Cod4

Call of Duty 4, Halo 3, and The Orange Box in that order. This also excluding sports titles.

It's a toss up between Oblivion, Call of Duty 4 and Halo  3

Mine has to be by far ESIV Oblivion. I've put 400 or so hours into that game. Probably because I entirely beat it around 3 times.

Guitar Hero III, and Smackdown vs. Raw 2007

Oblivion or Rainbow Six Vegas 1,Didn't bother with 2

TF2 (Orange Box)

My most played i'm guessing will have to be Oblivion. Believe it or not I think i must have played Skate the second longest, that game got so addictive.

I'd say Mass Effect. I seriously lost count of my playthroughs.

Halo 3 comes close second.

cod 4 has a little over 100 hrs, oblivion has at least 90 hrs, and im sure halo 3 has quite a lot of time logged in too.

for 360:
1. Elder Scrolls: oblivion.
2. Skate. ( Fun to just skate around while listening to the podcast etc.)
3. GTA IV.

Oblivion

I would have to say Call of Duty 4 is probably the most on the 360.  CS:S was probably my top played game of all time though.

I would have to say Oblivion.