Brushed steel, brass rivets and a marquee that hums. Drop a token and you are running the length of a citadel that floats above the cloud deck — the outer ramparts, the brass terraces, the hangar decks, the spire galleries and the citadel itself. Altitude is the whole game: climb over the walls, drop into the open band of a force field, and keep the tank alive by shooting the fuel drums on the deck. Hold all five sectors and the Postal Society will postmark your own Skyward Fortress stamp.

Left and right to steer across the deck, up and down to change altitude, space to fire. On a touch screen, drag anywhere — your height follows your finger and the guns fire while you hold.
Walls must be flown over, or slipped through the one open slot. Force fields leave a single band of altitude clear — the marker on the left gutter shows you where it is. Deck turrets only fire when you are low. Fuel drums are worth more than points.