Completing Super Mario Bros 3 - Without using Warp Zone.
The "traditional" way to complete Super Mario Bros 3 is to stock up on powerups, get a couple warp whistles and jump to the end. This allows the player to skip past the hellish worlds 6 & 7 which can be quite unforgiving.
Taking the most direct route, a seasoned player can beat the game in about 15 minutes...
But battling through every single world and making it to the end is something that most players haven't done...