Sky Raider

Sky Raider is a two-dimensional, vertical scrolling game. You get to be the pilot of a bomber whose task is to destroy as many targets as possible in the allotted period of time. Fortunately for the player, it is a target-rich environment and the best part is that there are no defenses to fly through. That means you get to bomb targets at will without fear of any enemy fire. Who could ask for a simpler type of game.