Here is a hack for Super Mario Bros. which has all the levels changed and some graphics modifications done to it as well! The levels were redone to give an added challenge to the game.
Super Mario Bros. (W) [!].nes - GOODNES 3.14
CRC32: 3337EC46
MD5: 811B027EAF99C2DEF7B933C5208636DE
SHA-1: EA343F4E445A9050D4B4FBAC2C77D0693B1D0922
SHA-256: F61548FDF1670CFFEFCC4F0B7BDCDD9EABA0C226E3B74F8666071496988248DE