"I wonder what they would call the NES Earthbound in North America."
"The infamous prototype dubbed it "Earthbound Zero". That makes the most sense anyway."
To be precise, the prototype didn't call it "Earthbound Zero", the fan-translators did.
The story, for anyone who hasn't heard it, goes like this. Nintendo translated Mother 1 for the NES, but never published it (for whatever reason). Somebody managed to get a prototype of "Earthbound for the NES" out of Nintendo HQ somehow at some point (I still can't believe how many people on the net seem to believe that it's a legit release, and that Nintendo only sold the one copy, but they still refer to it as a prototype), and sold it on eBay. At the time, a group was trying to hack the Japanese game in order to fan-translate it. They tracked down the guy who bought it, and gave him the money they had previously raised for hiring a translator, so he'd let them just copy the translated game. The ROM was unplayable as-is, so they had to hack it to get it to work. While they were at it, they changed the opening screen to "Earthbound Zero", which was what they were going to call their fan-translated version.
I've seen "Earthbound Zero prototypes" go up on eBay a few times since then, but they always show "Earthbound Zero" in their screenshots, which is the biggest giveaway that it's fake. It's either a complete ripoff, or it's someone who figured out how to copy a ROM onto a homemade cartrige.
I've also seen a couple of "prototypes" on eBay for Final Fantasy 2 and 3 for the NES. Always funny stuff.