Need a holiday game or two

[Amnestic]

So it's the holidays and rather than doing my essays I'm going to dig my way into games. Unfortunately, I seem to have this rather annoying habit of finishing games really quickly. I've knocked out both Crackdown 2 and Dead Rising 1 in a day each, finishing the majority of achievements in both with little inclination to go for 1000/1000 at this point. I'm looking for a game (preferably 360, though I have a pretty up to date gaming PC too) that'll give me something to dig into for a long time.

So, here's a list of games I've currently played:

Spoiler

Alan Wake
Alpha Protocol
Armored Core 4
Armored Core: For Answer
Assassin's Creed
Assassin's Creed 2
Battlestations: Pacific
Bioshock
Bioshock 2
BlazBlue: Calamity Trigger
Chromehounds
Crackdown 2
Darksiders
Dead Rising
(Dragon Age on the PC)
Dynasty Warriors: Gundam
Eternal Sonata
(Fallout 3 on PC. Want to wait until I upgrade it to get Fallout: New Vegas, so that's off the table)
Final Fantasy XIII
Gears of War 2
Grand Theft Auto IV
Halo 3
Halo 3: ODST
Halo Reach
Just Cause 2
Mass Effect
(Mass Effect 2 on PC)
Modern Warfare
Modern Warfare 2
Operation Flashpoint: Dragon Rising
Red Dead Redemption
Resident Evil 5
Samurai Warriors 2
Star Wars: The Force Unleashed
Warriors Orochi

-

Halo
Halo 2
Jade Empire
Mechassault 2: Lone Wolf

Additional Difficulty: I don't have access to Xbox LIVE right now and will likely not in the near future. Basically looking for a game which will occupy me for many hours.

Any ideas?

 

[Omikron009]

Assassin's Creed Brotherhood is awesome. There's a lot to do, the combat is way faster and more fun, and there's quite a bit of replay value to boot.

 

[ultrachicken]

Oblivion should be able to keep you occupied. Splinter Cell: Conviction isn't exactly long, but I'd recommend it to anyone. Far Cry 2 is also fairly addictive, if you can deal with the ridiculous amounts of driving.

 

[Stoink]

your best bet would probably be assassins creed brotherhood if you liked number 2
they finally added crossbows, ive been waiting for them since i saw it in the firsts intro : D

EDIT: also the orange box if you havnt played it already theres a LOT of replay value

 

[Neverhoodian]

I'd recommend Team Fortress 2. It's almost exclusively multiplayer, but it's the most fun I've had with an online game. The art style is unique, the gameplay is solid, and its over-the-top presentation is hilarious.

The only problem you might have is the game's difficulty curve. Many players like myself have played the game for literally years now, and we know all the intricacies of each class and map. Still, the community's generally more newb-friendly than most other online shooters. I'd recommend playing as the Medic first, as you'll be providing an important service to the team without worrying too much about combat. It will also give you a chance to observe the other classes in action.

Just get the PC version if you do decide to try it. The console versions are plagued with exploiters, and Valve hasn't bothered to update them.