Mega Man 2 is an action game developed and published by Capcom for the Nintendo Entertainment System. It was released in Japan in 1988 and in North America and PAL regions the following years. Mega Man 2 continues Mega Man's battle against the evil Dr. Wily and his rogue robots. It introduced graphical and gameplay changes, many of which became series staples.
Although sales for the original Mega Man were unimpressive, Capcom allowed the team to create a sequel. They worked concurrently on other Capcom projects, using their free time to develop the game, using unused content from the first game. Takashi Tateishi composed the soundtrack, with Yoshihiro Sakaguchi serving as a sound programmer.
Mega Man 2 is the best-selling Mega Man game, with more than 1.5 million copies sold. Critics praised its audio, visuals and gameplay as an improvement over the first game. Many publications rank Mega Man 2 as the best game in the series and one of the greatest video games of all time. It has also been re-released on several other consoles and made available on mobile phones.
Source: Wikipedia