Bubble Bobble is among the best arcade games ported for the Famicom and NES. The Famicom version happens to be nearly exactly the same as the NES version, with the only differences being a save option instead of passwords and an unfamiliar background on the EXTEND screen. Of course, Bubble Bobble was released only as a disk in Japan.

But there is a mystery still yet to be answered. Why does the Japanese poster for Bubble Bobble's FDS release show levels that are either slightly different or altogether missing from the Famicom and NES versions?

From the Japanese Bubble Bobble poster.