What is the EarthBound Zero prototype cartridge?

When Nintendo shelved the finished English Earth Bound in the early 1990s, a small number of prototype cartridges, reportedly six to twelve, remained in circulation. One surfaced at a game retailer, where collector Greg Mariotti found it, and in early 1998 he sold it to Kenny Brooks for $125.

Brooks's buyer timing mattered: fan translator Steve Demeter, known as Neo Demiforce, was then attempting a fan translation of Mother and negotiated access instead. The fan community donated $400 to loan the cartridge temporarily so its ROM could be copied. On April 27, 1998 the game appeared online as EarthBound Zero, the Zero added to the title screen by Demeter as a tribute to Street Fighter Zero, with small patches to run on period emulators.

For years the copy's authenticity was debated, and the cartridge itself settled it: the changes documented in the prototype, the run button, the expanded ending, later appeared officially in Mother 1+2, confirming the leaked ROM was Nintendo's real work. The physical cartridge, marked as a Nintendo of Canada evaluation copy, was later resold by Brooks for $1,000.

As an object it is the rare prototype whose chain of custody is fully public: found, sold for $125, loaned for $400 of fan money, copied, verified by its own contents. The Library keeps its history of the game elsewhere; this page is for the cartridge.