Rather than porting the games, for this title the original game files were used with an engine that uses hardware simulation routines that can then output them to any platform the engine supports. On top of that enhancements and filters are available for each game, such as aspect ratio (original, wide, and full) and two types of filters that are meant to replicate the original screens they are played on. It is possible to switch between the games quickly, each using their own save states next to the original password option.
There is a separate Challenge mode that remixes parts of the original games as challenges with quick mini-games with specific objectives. Some of these incorporate multiple games into a single challenge. The Museum mode holds a large collection of art and history about the games. There is also a music player with the original soundtrack for all games. The game also offers to fight any Robot Master right away with every weapon from the game. There are leaderboards, achievements / trophies and video replays that can be shared.
Retail release comes with a DLC voucher for soundtrack (containing 3 tracks from each game) which can be redeemed and downloaded from the official web site. Additionally, the retail release comes with four round stickers featuring Mega Man characters.
According to publisher Capcom, Mega Man: Legacy Collection has sold 1 million copies worldwide since its initial release (as of September 30, 2018).
At a 2019 GDC talk Producer and Designer of Mega Man Legacy CollectionFrank Cifaldi brings up a fan-made Mega Man hack called Roll-chan by Zynk Oxhyde which replaces Mega Man with his sister Roll. He states he tried to get in into the collection but the author didn't reply back.