True. It should have more levels with higher skilled enemies. Here, this one has tons of levels: Balloon Invasion
Ha!! This is JUST LIKE "Sopwith", which was my FIRST "airplane fighter" simulator/game back in the late 80's !! You could also in Sopwith, carry and drop bombs on the fuel tanks/tanks/bunkers/yourself/animals lol. It's also a two-player game or computer opponent. If you bombed the hill/mountains on either ends of the screen on the left or right, you could fly past and there was a secret programmed area with.....no..you'll need to find out yourself! Here's a copy of the game!