This is the second zone in Sonic 3 going through the game where it thinks you are playing as Knuckles. When you get to a certain point before Dr. Robotnik at the end of Act 2 you can either go Sonic or Knuckles route. I was able to go Knuckles route a bit. Broke through the wall then used a code to break the screen lock to go through the rest of the stage. It ends on a long row of spikes. So in part 2 you continue on Sonic's route to finish the boss.
There is not too much difference except a couple glitches. I just like playing through the game like this 'cause it's kinda whacky.
I was able to explore a really wacky glitch level on Sonic 3!! You are able to access Flying Battery Zone with a code but it's all glitched out then freezes. You can trick the game into thinking it is a different zone in level select using debug by hitting a goal post on one level then exiting and choosing another stage. So I was able to go to the glitched Flying Battery Zone and explore a little bit. I came out of Ice Cap Zone so it uses Ice Cap palette for the stage.
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