Astro3D II is a sequel to Astro3D. It features largely similar gameplay mechanics: the player controls a ship flying in space and must destroy various kinds of debris as well as enemy ships while collecting useful pickups. Unlike the first game however, which only featured 12 levels, Astro3D II can generate infinite levels for the player to complete.
The plot continues the story of the first game. The player resumes the role of a space pilot who has distinguished himself during the events of Astro3D. The Earth Alliance once again requires his services, this time in the exploration of the Infinite Expanse and its resources. The player must enter sectors of the Expanse one by one, and break up asteroids so that valuable Corbamite ore can be mined and then hauled back to Earth. Same ore can be used to refuel the ship while on a mission.