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Wily Wars USA ROM from Genesis Mini was edited, but restorable
Category: ROM data
Reference: 2406
Runex » 2020-06-22 11:43:43

The Megaman - The Wily Wars USA ROM from the Genesis Mini was clearly edited, but otherwise appears to be the legit USA ROM from the Sega Channel.

The likeliness that this isn't the lost USA ROM from the Sega Channel I believe is incredibly slim due to the overwhelming evidence that it is.

The only observable in-game change I've found is that the flashing effect when choosing a Robot Master Stage from the Stage Select was reduced from very rapid flashing to a few slow blinks (to anti-seizure it I'd bet).
They made the exact same changes, byte for byte, to the Jap ROM on the Mini as well.

Technical details:
The Serial Number is oddly the same as the Jap ROM, but perhaps from not having a physical release.
The addresses where identical data lines up is very very different from both the Jap and EU ROMs (all 3 are unique in that).
It also has it's own Security Checksum values completely different from the other region's ROMs.

Data-wise the game looks hacked on an assembly level, and I would presume it was by M2.
Its internal security checksum routine is disabled.
The checksums of both the Genesis Mini's Jap (has its originals) and USA ROMs don't match the data, neither the Genesis Header Checksum nor Wily War's internal set of Security Checksums (2 Bytes each - 0x200 - 0x21F, one for every 0x20000 Byte ROM section).

But if you do a hex compare search between the original Jap ROM from Cartridge & the Jap ROM on the Genesis Mini, those same changes can be reverted in the USA ROM, and then all of its checksums match the data perfectly!
The game then boots with its security checksum system working properly (and if a change is made from there, it will give you the red-screen of death).