The games that I think MIGHT sweep the award (for me personally) are:
1. Mirror's Edge - I have been looking forward to this game since I first read about it many EGM's ago, when nothing was known save for the title of the game and one single screen shot.
The shot was of Faith, the main character, sliding down the side of a glass building (click for the image -- its stunning) and I don't know what it was about that shot, but something just captivated me and since then I've seen nothing to deter me from getting this game -- it just keeps getting better every time its shown. While it utilizes industry standards such as platforming and a first person perspective, it takes these ideas and puts a very unique spin on them by not only COMBINING them to make what is essentially a first person platformer, but also in that the platforming serves as a means of puzzle solving. There are various routes throughout each level and its completely up to the player which route they choose, but each route is laid out in very subtle yet effective color codes to designate which routes are the toughest and vice versa. This is without a fraction of a doubt the game I'm most looking forward to playing this year. Here's hoping it doesn't let me down when it finally releases.
2. Rock Band 2 - Rock Band 1 is easily my most played game this generation. I'm playing it constantly and I've even racked up more play time in this game than I have with console staples like Halo 3 and CoD4. Rock Band 2, while essentially more of the same, is adding all kinds of little tweaks that will make the game that much more enjoyable, like online Band World Tour and the Battle of the Bands mode. The fact that solo careers are no longer just a stroll through a list of songs is just icing on the cake. But the real nail in the coffin is the fact that I'm going to have 80-some odd new songs to master on expert drums here in about two weeks, along with the slew of new DLC. I can't carp wait.
3. Fable 2 - I fell in love with the first Fable and Fable 2 seems to be taking everything that was great about the first game and making it better, while also trimming away all that was bad. The new drop-in/drop-out online co-op sounds AMAZING, particularly the bits where any player who comes into your world can completely change the fate of your world and its surroundings from their behavior. Fable was more or less the first RPG to get the "player choice/player freedom" right, and I have no reason to believe Fable 2 won't continue that.
4. Left 4 Dead - 4 player online co-op. Rabid zombies. I need not say anymore.
5. Prince of Persia - It looks amazing aesthetically and the gameplay and setting are very interesting. This isn't my top pick, but I definitely think this will be one of the more memorable games of this year.
As for games that have already come out this year that I think were impressive/could take the award:
- Burnout Paradise
- GTA IV
- MGS4 (Not a personal pick, but I think this game will win a lot of GOTY 2008 awards)
- Braid (Its an XBLA title so I'm not really sure if it qualifies, but its definitely been one of the best games I've played this year.)