Mario Bros. is a 1983 platform game developed and published for arcades by Nintendo. It was designed by Shigeru Miyamoto and Gunpei Yokoi, Nintendo's chief engineer. Italian plumber Mario and his twin brother Luigi exterminate creatures emerging from the sewers by knocking them upside-down and kicking them away. It is part of the Mario franchise, but originally began as a spin-off from the Donkey Kong series. Mario Bros. features two plumbers, Mario and Luigi, having to investigate the sewers of New York after strange creatures have been appearing down there. The objective of the game is to defeat all of the enemies in each phase. The mechanics of Mario Bros. involve only running and jumping. Unlike future Mario games, players cannot jump on enemies and squash them, unless they were already turned on their back. Each phase is a series of platforms with pipes at each corner of the screen, along with an object called a "POW" block in the center. Phases use wraparound, meaning that enemies and players that go off to one side will reappear on the opposite side. The game continues until the player loses all lives. Mario Bros. was initially a modest success in arcades, with an estimated 2,000 arcade cabinets sold in the United States by July 1983. It went on to be highly successful in American arcades. In Japan, Game Machine listed Mario Bros.