Best Xbox360 Game in your opinion?????

Definatly go for Assassin's Creed and COD4. The inginuity behing AC is amazing, and free running across rooftops never gets old. COD4 is short, but the gameplay is awesome, and the multiplayer is great. The biggest reason for the great multiplayer is that it is realistic...

Oh and if you like cars, racing, and the like, get Forza 2 if it doesnt come w/ your xbox.. great simulator

shooter = CoD4 or Halo3

RPG = Mass Effect

Action/Adventure = Assassins Creed

#1 Game = Mass Effect

For the new 360 owner, congratulations! As for your games...wow you have lots of catching up to do....lots of great games right now. As for the list of best games, here's mine.

RPG

1. Mass Effect - Best WRPG to date, amazing new RPG + SCI-FI + Shooter gameplay style.
2. Lost Odyssey - Released on Feb '08. If you are a JRPG fan, don't miss this.

1. Halo 3 - If you have the previous series, then surely you would want this. Great MP.
2. CoD 4 - Most popular in the MP world, simply the best.
3. GoW - If you have a 360, I can't see any reason why you shouldn't have this game. All time favorite.
4. HL2 :The Orange Box - 5 games for the price of 1? BEST deal out there, great gameplay too.

Tactical Shooter:

1. Rainbow Six: Vegas - Great shooter that is not run and gun type. Tactics is everything here, superb graphics!

Racing: These two are simply the best in this genre

1. Forza 2 - Sim Racer
2. PGR 4 - Arcade Racer

Adventure:

1. Assassin's Creed - Simply amazing.

Music/Rhythm

1. GH3 - Fun and addictive. Lots of replay value. Great wireless guitar.

Mass Effect.

No question or competition.

Best game: The Elder Scrolls IV : Oblivion, just awesome and epic

FPS games: Halo 3 for online fun and cooperative, Gears of War for cooperative, also Perfect Dark Zero was great but you can hardly found a macth now online (i miss those 32people sniper matches)

RPG; Eternal Sonata, again Oblivion, Blue Dragon (give it a try is kinda boring until the story gets a twist at the end of the disc 1, and the final boss is epic as Sephiroth was)

Adventure/Free roam: Assasins Creed, Saints Row (also online is fun), Naruto Rise of a Ninja (if you are a fan)

Action: Ace Combat

thos are my favs