Invinco is a Space Invaders clone released by Sega in 1979 for Arcades. This game innovate on the alien's behavior: one row blinks in and out of view, another row's aliens roll so as to make themselves harder or easier to hit, and a 3rd row of aliens each take (at least) 3 hits to kill. A 4th row has aliens that turn into bombs, blowing up everything around them to make your job somewhat easier.