This is a revision (Rev A) of Sa-Ga 2 - Hihou Densetsu for the Game Boy. Revisions often address bugs or balance issues present in the original release.  Without more specific information, it's difficult to elaborate on what changes were made between this version (Rev A) and the initial release of Sa-Ga 2 - Hihou Densetsu.  To provide a comprehensive introduction, details on the specific fixes and improvements included in Revision A would be beneficial.

Sa-Ga 2 - Hihou Densetsu (Japan) (Rev A)

Rubble Saver II (Japan)