Galaga is an arcade/action style space game. Your aim is to fire at the enemy ships until you destroy them. At the start of each game you have three lives. Be aware of the fact that there are three types of enemies. What you need is concentration and good reflexes.
The enemy ships are moving according to pre-defined trajectories, circles and semicircles whereas at the end they are aligned in rows. Then the ships start moving leftwards/rightwards till they reach the end of the window.Each time the enemies reach its edge all rows get one step closer to your position.
At the end of each level there is a bonus-ship. If you manage to hit it you will be able to get one of the following bonuses - stronger weapon, bonus live and super bullets, distroying two enemy ships at one shot.