Invaders Addition

Invaders Addition is an educational game where the player has to defend earth from an alien invasion. This is done by doing math. The player controls a gun at the bottom of the screen. From the top alien saucers will appear and move towards the player. On the saucer is an addition problem that the player has to figure out. If he types the right answer the alien will be shot down and another will appear. Input the wrong number and the alien will continue towards the player. It's game over when the alien reaches the player. The player wins if he manages to defend earth for two minutes. Before the game the player can choose a difficulty level. In the harder difficulties the aliens move faster and the problems are harder.