What game should i get for christmas?

Long Single Player Games:

Oblivion

Bioshick (depends on Level of Difficulty Between 10-20 hour Plus it has good Replay Value)

AC (You dont even have to do the missions and it is still fun)

Mass Effect (Never played it myself but i hear that is is pretty long)

Good Multiplayer

Halo 3

Gears of war

Shadow Run

Battelfield: Modern Combat (i think that you can buy this game at a good price)

Perfect Dar Zero (its only $20)