There were many games that turned into franchises, with a number of sequels and spin offs, that began their life on the NES. Some of these would grow in number and find their games on other systems too.
Mega Man 3 was released by Capcom in 1990. It was a follow up to the first 2 Mega Man games. Considered by many fans to be the pinnacle of the series. Gameplay was largely the same as the previous two.
Mega Man 3 added Rush and Protoman to the series, as well as introduce Mega Man's slide move, that would be present in many games after this. The tougher robot masters, combined with the extended castle was what made this a must own.