As a child in the 90’s I had the great pleasure of being introduced to the Nintendo entertainment system by my older brothers. All are familiar with the classic Italian plumber game as it gave unprecedented control over the gaming experience compared to its predecessors. Most people, if not all, know about the warp shortcuts that could be found in the first underground level at world 1-2 and throughout the game.

There are, however, a number of additional secret levels that exist in the original Super Mario Bros game that exist as part of the “negative world”. Growing up, I never met anyone who knew about these levels but they have become more widely known with the advent and widespread use of the World Wide Web.

I particularly remember when I was at a kiosk in a mall where one could play through Mario and buy Nintendo related products. The salesman pointed out to us that we missed the warp zone as we ran toward the exit tunnel. Then his bubble of pride was burst when we hopped upward while crouched and facing left; we then moonwalked backward through the wall to the warp zone. We went down the tunnel and found ourselves in Mario purgatory.

Welcome World -1-1: an endless looping underwater level made of extra code where you swim until time and lives run out. Quite a bit of a downer to die repeatedly if you ask most people, but still a nifty secret that deserves to be more well known.

On the Japanese release NES, hundreds of other levels in the negative world could be accessed and played, all made from extra code. If you would like to learn more about the negative world check out the video above!