Invinco

Invinco is a fixed shooter arcade game that was released by Sega in 1979, and licensed to Gremlin Industries for US manufacture and distribution; it runs on Sega's Vic Dual hardware, and is similar to their own Space Attack which was released earlier in the year as their answer to Taito Corporation's legendary Space Invaders. As in both of those two games, a player must use two buttons to direct a ship left and right (across the bottom of the screen), with a third button to make it fire shots up at the attacking aliens - but there are five different types of aliens worth 100, 200, 300, 400 and 800 points respectively as opposed to just three. Also, once you have killed the last alien, one "sky chariot" will appear and fly down the screen in a zigzag pattern while firing shots at you; if you are quick enough you can kill it before it kills you and proceed to the second stage. However, once you have killed the last alien for that stage, two sky chariots will appear - and if you manage to kill them and proceed to that third stage, three sky chariots will appear once you kill off the last alien for it. As well as being a standalone game, the game was also released in two dual cabinets with Head On 2 and Deep Scan (that latter game was never actually released by itself, and is similar to Gremlin's own Depthcharge).