Each player controls a little space ship startinf from the bottom of the screen. The ship can be moved up and down (but not sideways) using 2-direction joysticks. The ships must pass through an asteroid field that moves horizontally across the screen.
When a player reaches the top of screen, successfuly passing through the asteroid field, he scores one point. Timer counts down several minutes and whoever has the most points at the end wins. |source: old-computer.com]