The impending blockbuster--Call of Duty 4: Modern Warfare has sold over 13 million units, Call of Duty: World at War has now exceeded 11 million--has caused several other games to be delayed, including Call of Duty publisher Activision's own Singularity, as companies attempt to avoid going head-to-head with one of the year's biggest titles.
Infinity Ward's anticipated (and controversial) shooter sequel hits PC, PlayStation 3 and Xbox 360 in exactly one week, on Tuesday, November 10. Various retailers are hosting midnight events to commemorate the release, including GameStop and Walmart.
That game is out right now. It's called Borderlands.
You do not have to buy DLC to keep playing. You can play CoD4 MP right now just fine without the map pack.