> although curiously their NES emulator uses a ROM header format which originated in the unofficial emulation scene, so they must have used unofficial docs for reference.

Tomohiro Kawase, the guy who did the Animal Crossing NES emulator, was a part of the emulation community in the 90s and contributed to iNES. It makes sense that he kept using that header format when he started working at Nintendo.

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LocalH a day ago | parent [-]

I wouldn't even say that use of a header format itself is indicative of wrongdoing, even if Tomohiro hadn't went on to work for Nintendo.

However, if Nintendo had released any NES ROMs with a "DiskDude!" header? Then maybe. AFAIK this never happened though, and the big leak proved that they had a full final (and sometimes post-final or unreleased final) archive with split PRG/CHR, so they didn't need to use DiskDude! ROMs.

	▲	ndiddy 17 hours ago \| parent [-]
		Yeah I think it was just the developer working with what he was familiar with. For example, the emulator used for the 3DS NES Virtual Console titles was developed by a different team at iQue. It uses its own bespoke header format called TNES rather than the standard iNES header.