MARIO is a Super Mario World ROM hack pasta by SMW Central user Adam. The hack patch can be downloaded here. The patch itself is made by SMW Central user M A R I O, whose avatar is a SMW Mario without a face. He (she?) used to not to be seen as inactive (one month of no activity makes you inactive on SMW Central), as he (she?) posted mysterious and eerie things every now and then, just before he (she?) would turn inactive. As of recent, the SMW Central account has been disabled. You can find the original thread here. *Note: You CAN download that link in the thread*
This hack, being the first of its kind to hit SMW Central, of course gained a lot of attention, even the site's founder and Administrator Kieran (currently Kieran Menor), who then immediately recognized the .txt file, that Adam mistook for the .smc (ROM image) converted into .txt, as a .jpg file, due to its header. He tried manually converting it back into .jpg, but the result was barely viewable, the only recognizable part was the very top. He then continued searching Google for images with his attempt's resolution and the second result struck him as relevant. You can find Kieran's post here, his original attempt only displays a broken image now. This hack's novelty on SMW Central wore off however, and it was removed from the hack database after being accepted for being the first of its kind; a creepypasta hack. May be linked to.