The first Mega Man game was released in 1987. Developed and published by Capcom, it debuted in Japan for the Nintendo Family Computer on December 17, 1987, and later reached Western markets as an NES title.
Known as Rockman in Japan, the game introduced Capcom's side-scrolling action-platformer series. Its story follows Rock, a laboratory assistant created by Dr. Light, after he volunteers to become a fighting robot and stop Dr. Wily's reprogrammed Robot Masters. Players can choose the order in which they tackle the Robot Master stages, a design feature that became central to the franchise.
The original game is often confused with later Mega Man releases because the series eventually grew into several distinct timelines, including Mega Man X, Mega Man Legends, and Mega Man Battle Network. None of those later branches changes the answer: the original Classic-series game, and the franchise's first installment, dates to 1987.