Watchmen is a side-scrolling beat-em-up released for the arcades in 1988 by Atari Games. It is based on the 12-part comic book miniseries which was released in 1986 and it was published by DC Comics. It was distributed to arcades via two or four players. In 1989, a home console version was released for the NES by Tengen and it was unlicensed by Nintendo. At the same time, a handheld version was released for the unlicensed Game Boy by Tengen. It was ported to home computers in 1990 by Tengen. The unlicensed NES version is the best selling unlicensed game ever.