The shop is to buy items, look on the item button to see the price tag, and for upgrades look under the name for the buff. Every plane does not have the buff listed but they increase the price by either 5, 10, or 15. Click the plane to get money, to play the minigame click the blue (friendly) radar ping to get $10, if you click the red (enemy) radar ping you get -$100, and the minigame ends. (you don't have to rebuy it every time)
Me for code and most artwork. Google images for plane images. Me for ideas United States Air Force for inventing the planes in the first place.
