There is no other air combat game that puts you into Axis V Allied scenario situations and gives you the feeling of what it was really like to enter a battle with your squad.
In FSO for example, you are in a squad, you take off with the squad and fly for about 20 minutes getting alt. During this time, you chat with your squad, get to know them better, laugh and have a good time. Then all of the sudden you see the reds far out. Your adrenaline starts to kick in, the moment is there. You see about 15-20 enemies heading your way. The squad gets serious. Then some start to get shot down. You feel bad for them. You hear coms "multiple bogies" "check 6 check 6" and everyone gets into the combat spirit. Your hands are sweating, your body is trembling, your heart is pounding. You shoot down your first guy and feel so much thrill and gratification.
There's just nothing else like it. I love that about this game.