Magazine Previews/19
From Sonic Retro
Magazine Preview #19 - Special Stage in a Sonic 2 Prototype
Source: Unknown French Magazine
A prototype Special Stage, which doesn't seem very special. Don't mind the "Miles" text, that's what the game displays if a Japanese (possibly European too?) Mega Drive is detected. This is indeed a prototype because it came from the same source as M07 which has Hidden Palace.