I'm looking for an old arcade space game. It's beginning of the game is quite similar like Galaga and Galaxian. After the beginning, the second stage begin with flying saucers. I think the colour was red of that saucers. Then the third stage was with spacecraft like Galaxian but they do sometimes drop robots and they walk under the bottomline and pinch with something like spears above, try to hit your canon. The fourht and last stage was also with dropping robots but the spacecraft had shields with little gaps. To destroy that spacecraft you had to shoot in the gap. After that the whole cycle repeats.

Does any one knows the name of that game?????? Thanks a lot