Super Boy II is a 1989 clone of Super Mario Bros. created by the Korean pirate company Zemina (재미나, roughly translates to "It's fun!") and is the sequel to its earlier game, Super Boy I. Besides having bad controls and graphics, this game leaves out some of the original features, including warp zones, water levels, Worlds 5-8, and even the princess.
NitroGenesis shows off this tough game in its entirety, precisely avoiding all of the enemies and reaching the ending in just under six minutes.