I'm still working on this, but I wanted to go ahead and submit a rough draft so I could become formally submitted, and also get a little feedback. I'd like to make it a little longer and add some additional paths, and also pretty it up a bit (which I'll likely do in the next 2 week period).
Anyways...
Download: Attached
Title: Robotnik Park Zone
Credits: Thanks MotorRoach for getting the balloon popping sprites for me. Everything else by FuriousFox.
Maintainer Notes: 2 custom objects, Bumpers (461) and Balloons (462). The doomednums can be changed if necessary.
I had to get rid of the sloped roofs on the towers because they were crashing the game. Hopefully a future patch can fix that, or I can find a way to work around it.
EDIT: Sloped roofs fixed now (mostly). The crash was being caused by the end of the slope being 0-height, which SRB2's texture renderer didn't like. By making it 16-height now, it should be fine.
EDIT2: Apparently 16 wasn't enough, lets try 32. I tried several times and it didn't crash; hopefully it stays that way.
EDIT3: Nevermind. Reverted back to no sloped roofs. Made a small change to the balloon secret at the top of the bounce castle.
EDIT4: A bit more polish, plus a little work on extending the level.
EDIT5 : Added another room to the end, also smaller modifications throughout the rest of the level.
EDIT6: More rings and enemies. Minor texture fixes.