The Vintage Computing and Gaming website has done a neat synopsis on one of the best homebrew hacks ever, the most excellent 'Mario Adventure'.

Weblog writer RedWolf explains of the NES mod: "This isn’t your usual game hack, mind you. You’ll find no giant buttocks glued onto Mario’s forehead, no nude Mushroom Retainers, no Super Tokin’ Brothers with Luigi replaced by a white Rastafarian with a cannabis leaf for a hat. Nope, this is a real game — a new game, crafted with care and aplomb using the Super Mario Bros. 3 game engine."

He continues of the greatly enhanced title: "There are new graphics, new enemies, new enemy behaviors, new power-ups, new items, new rules, and tons of all-new, completely original levels. The game even uses SRAM, a la Zelda, (albeit only emulated at the moment) to save your progress in the game." Lots more info if you click through.