The marble ruins that were found
Sonic the Hedgehog for Master System and Game Gear is one of those games the community tend to forget in their research, centring their efforts in games more well known, but not anymore.
Sonic Retro user Kroc has found something very interesting digging in the complete Sonic 1 for Master System disassembly he is working on. Inside the game code, there was remainders of Marble Zone being playable in an older build. This could mean Sonic the Hedgehog 8 bits was once planned to have the same levels as the 16 bits version of the game, instead of having alternate levels like Bridge zone or Jungle zone. Kroc also points that he has found several pieces of evidence that hints to the game being once 512K in since, instead of the 256K of the final game, and of course, Marble Zone’s music, who is located between Green Hill’s and Jungle Zone’s in the code, making that a possibility that once there was no Bridge zone but Marble zone instead in that place.
Research is still going ahead, so we might have more surprises down the line soon. Meanwhile, you can listen to the Master System rendition of Marble Zone found in the game code.