Galaxy Wars is a variant of the space invaders genre with three different sub-games which increase in difficulty as you progress through the levels. I bought this game in 1984 and gave it some serious time although ultimately it was quite a repetetive game which didn't offer much challenge once you'd worked out the rhythms of the "invading" aliens.
Level 1, the horizontal space invaders that had a simple rhythm which was simple to time and destroy. As aliens wrapped around from the right to the left, they descended closer to the ground.
Level 3 - docking for fuel and more points. You had to guide your base ship to dock exactly in the centre of the mothership in the centre of the screen.
Once the docked, you're awared a points bonus which increases with each level you go through.
Level 5 - A repeat of level 2 with different sprites and background. The invaders move from horizontally whilst descending all the time. If they get to the bottom, they wrap around to the top again.