I think it's important to remember the context in which I released version 4, in that SRB2 itself had only a three zone demo, and those three zones were incredibly basic designs. Mystic Realm's "gimmicks" were basic things like "lava" and "ice", but we didn't have official stages that even used those basic concepts at the time, so the variety was a big deal.
Mystic Realm also presented itself as a complete game in its own right. While a lot of the stages I built are quite mediocre or even bad in hindsight, the package contained 7 full zones and a bunch of stuff to check out, with a suitable end sequence (even if the final boss was garbage in hindsight) and all the basic things you'd expect from a full game. Considering at the time SRB2 was a demo and clearly played like one, that is what gave it such popularity at the time.
One thing I never did like in Mystic Realm though was how the Mystic Temples funneled players who knew about them down very specific routes through the act 2 of a given zone, so the alternate paths became clearly worse choices once you knew where all the temples were, because you'd be missing out on the Emerald stages if you took a path without a Mystic Temple on.
Yep, this always bothered me a lot in hindsight, too.
The 2.2 port addresses this and a bunch of other similar "this always bothered me" things, basically. It's delayed currently because I'm waiting for a couple things from people who are currently busy, but a basic overall list of changes so far:
- Reworked all the liquids such that things that actually look painful hurt. No more "toxic mud" and "cold water" nonsense. No more instant death slime. All of the liquids act like they do in vanilla at all times.
- Modern emblems instead of the old character ones.
- Moved some of the shrines so they're all on shared routes.
- Split the new 2.2 AGZ into acts and inserted it back in.
- Edited sections so the package is beatable by the new vanilla characters.
- Deleted the archives because it was a terrible idea and god dammit stop copying my worst ideas you guys :(
- Fixed a bunch of minor gripes and issues
The bosses still haven't been addressed as getting time to talk things over and code that stuff is the main thing the port is waiting on. There's also a WIP Prismatic Angel Zone Act 2 to finally finish what I never did in 2005, but I'll only include it if the results actually turn out at least okay.
tl;dr: it's not anything close to a 2.2 level of insanity; I could never do such a thing on my own. It's more of a "it's been 15 years and I'm well aware of what parts of this are really bad ideas, so I should fix that" set of changes.