This is a classic defender type game but with droids. The goal of the game is to shoot as many of the droids as you can to unlock the next level and get a high score.
Use the up and down buttons to position the ship and the shoot button to kill the droids. The first objective is to kill enough droids to unlock the next level and the second is to get the highest score. Bullets that do not hit anything take points away from your score so use them wisely.