If you really just want to hear what I'd come up with -- and keep in mind this is like 3-4 years old at this point, scroll down to the bold text, but you'll miss what I think is a fairly interesting story.
Hahaha, this is probably the most insane music coincidence possible ever really -- I was, about 3-4 years ago working on a MIDI remix project of a bunch of tunes from Sonic 3 -- largely for the sake of making them sound better than the music in Sonic and Knuckles Collection for PC. You can probably find some of the songs on youtube if you look.
Although my first couple songs were songs from Sonic 3 that got replaced by slightly-less-awesome tunage in the game (the Sonic 3 credits and Ice Cap Zone are a couple notable examples), it quickly ballooned into a general let's-remix-everything-in-the-game project. But it didn't ever get completed because I am lazy, easily distracted, and moved on to other things.
Anyway, one of the songs was Mushroom Hill Zone -- original song can be found here (act 1) and here (act 2) but if you'd like to hear the versions from the PC collection, you can go here and here but I should warn you these are recorded off the default roland sound canvas most PCs use. If you've got a better player you might want to trawl around for the actual MIDIs from the game, which have been ripped and can be found around the internet somewhere, I'm sure...
There was also a remix version of the song on an album, found here. The album's actually pretty crappy but amusing because of it -- good for one or two listens. It also only has S&K music, but there are little bits added on here and there in a couple places. My goal was, in some of the transitions, to add in a couple references to this album inasmuch as it was apparently official/licensed. Also if I could make references to other songs in Sonic or even other Sega games, I'd do it.
Now, my rendition of the song sounded a bit different from all of these, naturally. I added a lot of dischord because I felt that the zone was meant to be a bit hyperactive, fast, and somewhat of a bad trip (I mean, giant mushrooms? Sounds like a particularly strong surreal fever dream to me!). Now, the song's still at more-or-less the same tempo as the original, but it's got a lot of odd things going on in the background an dissonances here and there.
If you'd like to listen to my version, it's right here: http://www.box.net/shared/8a9sbpvelo (please share if you like it)
Now, the funny thing is that *after* making this, I realized that I had forgotten one potential source for material -- there was another instance of Mushroom Hill Zone, in the lesser-known video game Sonic the Fighters. Now I've still never played the game and hadn't heard any of the music at the time, so I was a little upset I'd looked over potential source material. So I took a listen to it.
Uncanny, yet again. Similar instrumentation, lots of bends upward like in my version of the song, some chromaticism in the background like my song. Holy crap, I apparently referenced it without ever hearing the damn song in the first place. I am entirely amazed that this happened and was laughing for a good long time (in fact I am right now giggling to myself a little at it, having gone back and listened to it again).
I'm not really sure how to explain the similarity. I can't recall ever hearing the song before that point. It's not something that was necessarily a consistent style choice throughout the rest of the project. I'm actually not sure how I feel about the rendition itself at this point -- like the album of S&K remix tunes it seems mainly something to listen to, chuckle if you've heard the Fighters soundtrack, and then file away in the recycle bin.
Anyway, if you'd like to hear the other 6-or-so songs that I made before basically putting the project on an indefinite hiatus, feel free to comment or something. I can link to them fairly easily, and will put in a little description or something even maybe.