Why did some copies of WWF No Mercy erase your saves?

The problem lived in the game's save system on the earliest cartridges. Players would return to No Mercy and find their data gone, inexplicably erased: championship progress, everything bought in the SmackDown Mall, and the created wrestlers that players had spent hours building. On a game whose whole appeal was accumulation, the bug struck the exact thing players valued most.

THQ's first response was a workaround, not a fix: reset the cartridge to its factory defaults, a procedure that could stop the erasing but cost players their existing data in the process. When that proved unsatisfying, THQ ran an exchange program, dated to around March 2001 in fan documentation of the recall, under which owners sent in a faulty cartridge and received a corrected one.

The corrected version was never sold at retail. It exists only because individual owners bothered to mail a cartridge back, which is why collectors treat it as exceedingly rare and why fixed copies change hands for hundreds of dollars. The revision also removed the visible blood from the game, a change the second European release shared.

Collector knowledge adds a tell: fixed North American cartridges are identified by a 'USA-1' code on the label, the mark of the revised production run. It is the rare case of a bug fix becoming the collectible. The broken version is the common one, and the cartridge that simply works is the prize.