This version of Zero the Kamikaze Squirrel is identified as Revision A, indicating a later release or updated version compared to the original. It suggests bug fixes, minor adjustments, or potential improvements over the initial European release.  More information on specific changes is needed. The developer and publisher remain unknown without further investigation.

Zero the Kamikaze Squirrel (Europe) (Rev A)

Zero 4 Champ RR (Japan)