This is the real Super Mario Bros. 2, the direct sequel released only in Japan. It looks and sounds like the first game, but it is a brutal test of skill. It is absolutely worth playing for the challenge, but know what you are getting into.
The gameplay demands fast reflexes and perfect timing. It is famously tough, filled with cruel traps, tricky jumps, and poison mushrooms disguised as power-ups. Be prepared to die a lot. Conquering it is a true badge of honor for any NES player.