As an avid defender of the Emerald Hunt stages, I'm surprised I didn't hear of this one sooner.
Tried it out and yeah, it's pretty nice. The menus are pretty clean, the Tikal sprite is cute, setting the music selection to random makes repeat playthroughs more bearable, and there's even a ranking system.
Speaking of the ranking system...
THIS HACK IS BRUTAL!!!
I managed to get an A-rank on Emerald Hill after about 30-ish attempts and it really was by the skin on my teeth. It's almost comical how hard it is to A-rank a stage.
The game wants nothing but pure perfection when it comes to overall time and rings, and you might as well re-start the ROM if you get hit because you're not getting that A-rank otherwise. (Although it's cute that the "SEGA" voice line when booting up the game changes voices depending on if you've picked Knuckles or Tikal in your last playthrough).
And another obstacle is just the inherent jank with Knuckles in Sonic 2, like climbing often not working right, the reduced jump height making it really hard to hit enemies and secret walls you can run through are almost impossible to do so. Not to mention since you can't look around in a 3D world like the Adventure games, it takes a lot more memorizing to figure out where an emerald shard is since you can't see one off in the distance.
Best strategy I found was to path out a route with a lot of rings and hope the emerald shards spawn conveniently on the way and just
praying I don't get hit anywhere on the way, as well as so the shards don't spawn too close together so you don't have time to gather that many rings.
It feels very different from how Emerald Hunt stages are in the Adventure games, where they're more free-form and about improvising your way to each emerald shard, whereas here since you're punished so hard for a single mistake, it does feel like a bit of luck since an emerald shard in a hard-to-reach place is a guaranteed lost A-rank.
I don't take this as a complete knock against the hack, by the way. I'm a big fan of difficult games that drive me to perfect them, just wish there was a little less luck involved, as well as a quick-restart feature so I don't have to reset the whole thing if I mess up. But even then it's still very well made and a welcome change in playstyle for a hack as well.