Complex sentence: Players who succeed receive an in-game certificate as well as a gift (varing on the rhythm game); if they obtain all certificates, they get a special certificate as well as access to all songs in the drum mode.
Split into simpler sentences: Players who succeed receive an in-game certificate as well as a gift (varing on the rhythm game). If they obtain all certificates, they get a special certificate as well as access to all songs in the drum mode.