This version of Puzzle Bobble 4, released in arcades in 1997 by Taito, is likely a variant released for a specific region or representing a minor update compared to other versions. The 2.04O designation hints at a possible revision or optimization. The fundamental gameplay—the bubble-shooting puzzle mechanics that defined the series—would be consistent across versions.  What distinguished this version might be small details in the graphics or subtle gameplay adjustments.

Puzzle Bobble 4 (Ver 2.04O 1997/12/19)

Puzzle Bobble 3 (Ver 2.1O 1996/09/27)