Star Soldier: Vanishing Earth takes place in the far future, where you are the last hope for Earth, which is being attacked by an alien race. The game features a top-down 3D scroller, similar to that of the arcade games 1943 or Raiden. You can take control of different space crafts, each with different advantages and disadvantages, and different weapons. The rule is 1 hit-kill. After 3 lives, you have to restart the level. There is no saving feature, however a lengthy password is provided to you at the end of each level, so long you have the patience to put it in each time you turn off the game.
Each level is about 3-5 minutes long, each with it's own tough boss at the end. Each level has its own secret path to take, depending on what you shoot (ex. shoot wall, reveal secret path). All levels lead up to a final boss in the end.