SMW hacking
From SMWiki
Super Mario World hacking is the process of changing the SMW ROM from its original state. This is usually done through the use of a hex editor or the multi-purpose editor Lunar Magic. SMW hacking is done on many boards, the place with the most to help you can get with your SMW hacking needs is SMW Central. It offers you documents for help, patches that you can apply to make it interesting, custom blocks, sprites and music that you can use, ExGFX that you can put in to make it look different, and Tools that will allow you to change many things.
