Played the 1.08 version, just finished, maybe a few tips to improve
First, The Insta Shield, it works nicely but it lacks just that "invincibility-frame" that made it so special on S3&K, it allowed you to kill these spikey enemies and dodge damage , here on this game seeing how difficult it is, I please beg you, to add that , it is completely unfair sometimes
General Level Design: Sonic CD had that problem where if you went fast, a enemy was waiting and then you just got hit by it, same here, happens waaaaaay a lot, maybe even a Stage Hazard sometimes.
The Special Stages, the biggest bruh , can't make it, I got the first one legit and then the rest I couldn't, i had to resort to Cheat Engine to get the 7 emeralds, otherwise it wouldn't have been possible
Gene Gadget Act 1 and 2 are a super maze, the fact you can actually move through tubes on Act 1 was something it took me a while to figure out, the first act boss fight, is just extra difficult, worth of being a final boss honestly restarted the stage just to gring Rings and Super Sonic it out, else impossible, maybe add 1 ring after defeating of them? or make it so they spawn over time. The Act 2 boss was alright though
Panic Puppet Act 1: Insane maze, took me 8 minutes to reach the boss and i couldn't kill it due to a time over, had to consume a extra life for it to reset, now the Act 1 boss, Horrible beyond Horrible, i get the idea but, it's just so darn difficult, being hit once just renders you useless as the rings just fall off and tails movement is slow, and to make it worse, there's a second phase, which is even more unfair due to the plus that tails moves slow, and robotnik can just, appear from the bottom side or top side, maybe restrict it to being only left and right, or just add over time a ring that shows up so you have a chance, more than that, i see that boss to being improved, I legit had to reset the stage just to grab rings and Super Sonic it out.
Panic Puppet Act 2: was alright, fun to explore, the first phase of the boss really meme, hits you a lot, maybe add a delay after they stomp? most of the times i just got hit after hitting the boss, which was meh, took me a few tries, the second phase, just add more time to hit the blue orbs pls, third phase was alright
The Final Fight: 3 minute boss , really easy tbh, just time consuming like the original one, dying here and on the post fight is just... eehhhh, since you have to repeat that over again and it's just frustration at that point.
Extra Boss: what if we got more rings ? , I spammed the Boost because I got a vibe from S3&K, though it consumed rings so I found myself in a weird spot and then died, The Character's movement seem slow too, but overall a fun fight and a nice touch to the end of the game.
That's all my rant of the game, hope seeing it improve.