Gears Of War
Where to start? Well gears of war is most definitely the best game so far that has reached the current gen consoles. I will give you a relatively short, but sweet review of why GoW is imo GOTD.
Starting with the single player, it is just the right length; most surely not too short and not too long either (which is probably more annoying, I mean come on; who doesn't have 10 games in their collection that are so long that they have been dumped?). You feel like you have accomplished something incredibly awesome when you complete in on insane and the final cut scene just tops it off. The AI are pretty clever, but nothing particularly special except for when they work in groups. The programming is very good however at some points you do feel like you are just repelling 'waves' of enemies. Co-operative play is brilliant, especially when you know the person you are playing with; but is still fun if you don't and an easy way of making online friends.
The multi player; all you need to do now is ask ANYONE who has ever played Gears of War online especially ranked for a minimum of 10 hours and they will tell you how intensely amazing this online experience really is. You actually sometimes feel like you are in the game because of the unreal sound effects and incredulous visual effects (roadie running aka holding A, with the volume on max on an HDTV will blow you away). Obviously it is not perfect, no online games are because there are always people will ruin the experience for others even when there is no gain for them to do so. However, most of the time the people you meet are friendly (unless you provoke them) and are all healthily competitive.
The best graphics, the best sound effects, the most originality, the best online, the best offline. The best game of this decade and will be looked back on as one of the greatest of all time, undoubtedly.