Here is a hack for Super Mario Bros. adds a new type of block to the game and demonstrates it with one level of play. The block bounces Mario off when he makes contact with it. This hack would be great for anyone who wishes to make a full hack using the code for these blocks.
Super Mario Bros. (World).nes - NOINTRO
CRC32: 3337EC46
MD5: 811B027EAF99C2DEF7B933C5208636DE
SHA-1: EA343F4E445A9050D4B4FBAC2C77D0693B1D0922
SHA-256: F61548FDF1670CFFEFCC4F0B7BDCDD9EABA0C226E3B74F8666071496988248DE