Rockman 4 is a platform game developed and published by Capcom for the Famicom/NES. It was released in the US as Mega Man 4. Released: (JP) December 6, 1991 (NA) January 1992
Rockman World 2 is a platform game developed by Japan System House and published by Capcom for the Game Boy. It was released in the US as Mega Man II. Released: (JP) December 20, 1991 (NA) February 1992