Decomp: https://github.com/Rubberduckycooly/Sonic-CD-11-Decompilation
Mods used:
Sonic CD Separated Past Themes - SoN1c2001, US Past Themes by KingMeteorStudios
Higher Quality JP/US Music Mod - Darkskull Dawn Zenith
Restart Special Stages/Time Attack - MegAmi
1996 PC Title Screen - RetroForever
Collision Chaos is Sonic CD's version of Spring Yard. Spring Yard was after Marble Zone, wasn't it?
Sonic CD at one point did have its own take on Marble Zone, the cut "R2". A snippet of it can be seen in the animated ending montage, and it's known to feature rainbow waterfalls. It was apparently removed due to not being great to play, but supposedly, bits of it were merged into Tidal Tempest and the Wacky Workbench easter egg room.
At this time, Mr. Freaks has 531 views for Sonic CD spread across 43 videos. About an hours worth of Sonic CD videos were uploaded to his channel, or 2.40% of the total watchable video on Mr. Freaks's YouTube channel.