Take yourself on a ride back to the year 1980, when games came bundled with calculators rather then iPhones.

Score points by matching your spaceship number with one of approaching invaders and press fire to blast it from the screen. Should the sum of the numbers that you’ve shot reach a multiple of 10 the mysterious mothership will appear, giving you the chance to earn bonus points.

Each level has a wave of 16 invaders that you’ll need to shoot down. The invaders moving progressively faster with each higher level, so keep those fingers flexed and nimble.