""Jack Bros., known in Japan as Jack Bros. no Meiro de Hīhō! (ジャック・ブラザースの迷路でヒーホー!, lit. "Jack Brothers' Hee-Ho at the Labyrinth!"), is the only video game developed and published by Atlus for the Virtual Boy console in 1995; its pre-production name was Devil Busters, which was soon changed.
The Jack Bros. are the two mascot characters of the Megami Tensei franchise. They have appeared as silly, comedic characters in many of the games, and have been both opponents and allies (the "Hīhō", or "Hee-haw", in the title refers to the characters' signature laugh). One brother is a snowman called Jack Frost, the other a pumpkin named Jack Lantern (Pyro Jack). The game adds a third brother, Jack the Ripper, renamed Jack Skelton in the North American release--strangely, this spin-off title was the first Megami Tensei game to be officially translated into English and released in North America.
The story of the Virtual Boy game is that the brothers have taken advantage of Halloween to leave the fairy realm and haunt the real world; unfortunately, they have lost track of time, and must now find their way back to fairyland by midnight or be banished from it forever. The game is played in an overhead style similar to the Gauntlet series--three-dimensional Virtual Boy enhancements and monochrome restrictions notwithstanding --and is divided into six stages. Each stage has a strict time limit, which is reduced every time the player gets hit.""
Source: Wikipedia, "Jack_Bros.," available under the CC-BY-SA License.