Megankreuzstilette is a ROM hack of Mega Man 3 and is also a modification of a bugfix and improvement ROM hack known as Mega Man 3 Improvement. The name is a portmanteau of Mega Man and Rosenkreuzstilette, though the romhack itself barely has anything to do with the latter video game series beyond having a medieval aesthetic. Despite the name, the modified graphics and music, and the addition of multiple paths that can be taken in each stage, the gameplay itself and the level design is mostly unchanged from the original Mega Man 3.
longbao here goes through this romhack and beats it as fast as possible.