A hack of Super Mario Bros 1 featuring Demo, a character created by Raocow.
Simply changes player graphics and some palettes around, and some minor text edits elsewhere.
Super Mario Bros. (Japan, USA).nes
CRC32: 3337ec46
MD5: 811b027eaf99c2def7b933c5208636de
SHA-1: ea343f4e445a9050d4b4fbac2c77d0693b1d0922