"Progear" is a steampunk-themed horizontally scrolling bullet hell game where players assume the role of children controlling a plane equipped with the titular propelling engine through five stages in order to overthrow the Metoruin sages and their new world order. At the start, players are given the option to choose between two pilots (planes) and three co-pilots (gunners), each with their own advantages and weaknesses which determines the effectiveness of their respective modes, in addition to changing character's costume and formation of gunners by performing specific button commands at the selection screen.