Galaga is an arcade fixed-shooter game where the player controls a spaceship at the bottom of the screen.
The player is in charge of a starfighter that can move left and right along the bottom of the playfield. Near the top of the screen, enemies gather in groups and make a shape. They then fly down toward the player, shooting at them and trying to crash into them. In later rounds, some enemies will even break away from a group of enemies coming in and try to crash into the player as fast as they can. The game is over when the player's last fighter is killed by an enemy, one of its shots, or by being taken by an enemy.
Have fun and good luck!