Ace Combat X: Skies of Deception (Action Flight Simulator)
Got a good review on IGN - would like to post the link... but I am yet not allowed
There are 15 Missions to fly which results in a flight time of about 2 hours only. But some are quite tough and all are very different. It took me about 8hours total.
The game has some kind of achievment system which allows you to access and buy new airplanes and parts. After the first time through the game you certainly want to try it on hard with all the new airplanes and parts you have not had from the beginning...
If you have not played it, get Patapon... very funny great game, great bargain!!!