BaRaDuke

Baraduke (バラデューク) (Also called Alien Sector) is a scrolling shooter arcade game that was released by Namco in 1985. It runs on Namco Pac-Land hardware but with a video system like that used in Metro-Cross and Dragon Buster.

The player takes control of a spaceman in a bio-suit, player 1 is Kissy and player 2 is Takky. You must clear a total of 8 progressively harder floors, or stages, which each consists of 5 regular levels and one boss level. There are a total of 48 levels. Press the fire button to fire your wave gun at enemies. Save the one-eyed Paccets for points and a chance for another shield at the end of level bonus game. In each level there are a certain amount of enemies named Octy, which when defeated will yield power-up capsules. Defeating all of the Octy in a level will open up the gate. Go into the gate in order to end the level. After you complete 5 levels, you will enter the boss stage and after the boss character is defeated, you will go to the next stage.

Source: Wikipedia, "Baraduke", available under the CC-BY-SA License.