Zybex (1988)

A horizontally scrolling 'always firing' shoot 'em up game with an emphasis on power ups and notable for the fire button only being used to change weapon. The player takes the role of one of two convicts; Rinser and Cassalana, escaping from an execution in intergalactic prison. To buy their freedom, players must collect tokens to open later levels by destroying the large end of level bosses.