Gunball: Emperor's Revenge is a game in the Gunball series. It's a fighting game that takes place in a land populated by spherical combat robots called Gunballs that are outfitted with various weapons.

The land of the Gunballs is ruled by a tyrannical Emperor who has issued a challenge: anyone who is able to defeat him in battle can take his place on the throne. With so many loyal followers among his ranks, the Emperor is not worried about losing his position of absolute power; unfortunately for him, though, one small Gunball has accepted the Emperor's challenge and is on his way to destroy the Emperor...