Rockman Complete Works: Rockman 4 is a port of the Japanese version of Mega Man 4 for the NES. Some of the notable differences include less lag, faster weapon swap, different usage of Balloon, Wire and Rush Jet which are helpful for frequent zips throughout most stages, including the Boss Rush skip, and a reworked soundtrack using CD quality audio.
While it is usually preferred to choose Navi mode for Rockman Complete Works games thanks to its features, Baddap1 opted to stay in Original mode as it is necessary for Boss Rush skip in Wily 3 due to how the pause menu work in Navi mode. See author's comments for more details.