Air Raid! is a side-scrolling shooter which puts you in control of an aircraft and charged with the task of defending a city against waves of incoming bombers. Each level starts with your plane fully fueled and loaded with ammo, waiting for take-off. The bombers appear on radar in the distance to your left, and you must destroy them all before they take out your radar and both of your landing areas.
There are a total of nine levels, or "strikes" of increasing difficulty. On the first, there are only a small number of bombers, which cannot return fire. Subsequent levels have increasing numbers of bombers, some of which can shoot back. Later levels also introduce fighter escorts which move faster than the bombers and will change course to intercept you. Each level consists of two waves, with the second wave appearing only after the first has been cleared from the air. After the ninth strike, the final level repeats until all of your planes are destroyed.
Flying uses fuel, and shooting reduces ammunition. These can be replenished, up to a maximum of 100 units each, by landing on one of your air bases. Whilst flying, you also have the option of dropping an external fuel-tank. This decreases your fuel to 50, thereby reducing your flight time but also improving the speed of your aircraft.