Super Mario Bros. (SMB) is one of the best-selling videogames with more than 40 million copies sold. In the 30 years since its first release, SMB has been almost universally lauded for the inventiveness of its audiovisual, level and interaction design. World -1 cannot truly be said to have been designed by anybody whether Nintendo employee or fan as, while its audiovisual and gameplay elements are drawn from the game's repository, the level is actually procedurally generated through unintended interactions in SMB's code. The appearance of the 1-Up Mushroom in the middle of World 1-2 transforms the potential function and operation of the ceiling blocks. Wall-ejection is SMB's mechanism to push Mario out of a wall when he entered it partially. For three decades, Nintendo has exhibited a quiet yet ambivalent attitude towards World -1. The continued existence of World -1 in the emulated versions of SMB symbolically communicates the unaltered authenticity of the release, warts and all.