Galaxion is a fixed screen shoot 'em up. The game is as can be expected inspired by the arcade game Galaxian but here invaders only descends toward the player after they have been shot. Before that the invaders only move back and forth in a formation of six rows. The player can get killed by colliding with a descending alien or by getting hit by a projectile. The game ends when all three lives are lost. When all enemies have been killed the game moves on to a new level which plays in the same way. Before starting out it is possible to choose the speed of the attackers as well as the density of their missiles.