O.K. don't laugh me off the forums but Smart Bomb is coming out with a new Snoopy Vs Red Baron game. Disclaimer - I DO NOT WORK FOR SMART BOMB - End Disclaimer.
I have been a Peanuts fan my whole life and especially a fan of Snoopy. I always got a kick out of his WWI flying ace bits so when I saw the original Snoopy Vs. The Red Baron game I picked up a copy and have had a blast with it. It is based on a cartoon strip so you absolutely have to come at this not expecting a real world flight sim game. It is done in very bright colors, the planes are cartoony and the controls are absolutely designed for an arcade game not a real world flight sim like Rise of Flight or Over Flander's Field, you can practically hang in mid air using your speed brake! The weapons are aimed at kids, i.e. the pumpkin gun, The bee gun, bottle rockets, flaming boomerang, rockets that you can steer as Woodstock, etc. And a machine gun that has unlimited ammo and never jams.
I have been having a good time with it, I got it to play with my grandson to introduce him to Snoopy and the gang but he doesn't like flying games, but he does like to watch me play.
I saw an ad for the new version of the game, Snoopy Flying Ace, and took a look at the game trailer on their web site, http://www.snoopyflyingace.com/. The graphics are worlds better, it looks to have more of a role playing aspect to it since you can play as Snoopy outside of his airplanes.
If you like WWI flight sims and if you are looking for a just plain fun flying game I can very strongly suggest Snoopy Vs. The Red Baron. The new game isn't out yet but it looks great, at least on video.