The Classic series' only 32-bit game.
The Sega Saturn version had Cut Man and Wood Man (Rockman 1 and 2, respectively), return as sub-bosses.
Tengu Man and Astro Man return as robot leaders in the side-story sequel, Mega Man and Bass. This makes them the only robot masters that have ever been reprised in the series (at least as far as the "8 main" robot masters in a game go.)
In North America, the game was released as a 10th Anniversary Collection. The PlayStation version contained an Anthology Booklet (a watch was later added), and the Saturn version held exclusive artwork.
Contrary to popular belief, this game was NOT the first appearance of Duo. He previously appeared in the then arcade-only Power Fighters (this game has since been released on home consoles as a part of the Anniversary Collection.)