ClayFighter 63⅓ is a fighting video game developed and published by Interplay Productions for the Nintendo 64 (N64) video game console in 1997.

The Isle of Klaymodo is the resting place of "Bessie", the purple meteor that came crashing out of the sky onto Klaymodo Island. Bessie has the essential ingredient, Bawk Choy, necessary for Dr. Kiln's world dominating Mutagen. Klaymodo's chief baddies are the devious Dr. Kiln and local voodist Happy Harry Houngan.

With a combination of laboratory experiments and voodoo spells, they've created an "interesting" assortment of hooligans to help them take over the world. These hideous henchmen include Bonker, a clown gone bad, and Ickybod Clay, the wonder from down under. Dr. Kiln is putting on the finishing touches on his top secret mutagen code named "Clayotic Claymorphisis" as Houngan walks through the lab door. When Houngan finds out about Dr. Kiln's secret formula the clay hits the fan. As the fight breaks loose the vial containing the mutagen breaks in Dr. Kiln's hand and begins to take on a life of its own.