In terms of positives, I really liked the level design and their tropes, as well as the fact that the controls and physics felt pretty much spot on, so it felt great playing it. Not counting the games using Taxman's Retro Engine this by far feels like the most accurate 2D Sonic fan game so far, at the very least comparing to the few finished ones. I also really liked the new shields and how they were balanced; the fact that the rock one can be used as a projectile is extremely useful and that after using up both rocks you have to wait a bit until being able to chuck them again keeps it from being too overpowered. The wind shield was really useful and losing flight after hitting a wall or ceiling, again keeps it from being too overpowered, also I appreciate the nod to Nights. The fire shield leaving flame trails when you run fast is a really neat graphical detail, and the fact that the bubble shield's bounce is affected by slopes just like it is in Mania is also something I love from a gameplay standpoint. The Special Stages and how you get to them is also something I really liked. The concept is pretty creative and I found them pretty fun to go through, and as someone who played this on a keyboard I think they controlled fine, though it might be a good idea to add an auto run option for those who use controllers, since I've heard multiple times from them that the Special Stages control awkwardly. And one more thing I want to gush over is your implementation for Super Sonic, I absolutely adore that you need to use two jump buttons to transform and can also transform back to normal at any time with the same method. I also love the fact that you can use shield abilities while in super form and also the fact that Super Sonic does not replace the level music, just overall great stuff there, man.
In terms of negatives, I didn't really see a point in using the ice shield, since in order to freeze enemies you have to get really close to them and at that point you might as well just destroy them then and there, since enemies still do collision damage when frozen. I dunno, maybe it's meant to be used against the multi-hit enemies? Never got the chance to try it out on them so I have no idea if it's more useful on them. This leads to my next complaint, the multi-hit enemies. I don't really see much of a point to them besides ruining the pace of the level, they just feel unnecessary, since they're not difficult to take out at all. The time travel aspect is kind of a half compliment and half complaint, I like how easy and quick it is to time travel compared to Sonic CD, but on the other hand I don't really like that a lot of the past/future signposts are placed in the middle of fast sections. The reason why that's a problem is unless you're already aware where they are you have go through the level really slowly if you don't want to time travel, which at some points was my case, since I was hunting for Time Stones and Chaos Emeralds, which are tied to the past and future respectively. I liked the fact that you can cancel time travel if you jump before finishing turning around the signpost and using the same one in case you change your mind, but considering how fast some of these sections get it can be really hard to react on time unless you already know they're there. Also having a few more past and future sign posts scattered through out the levels might have made it a bit more bearable if you do accidentally time travel, because it felt like there was too few of them. Also in terms of the true ending, what the hell was that? Fan game or not that was completely out of place for a Sonic game.
I also had some technical issues, the first one happened in Raging Ruins Act 2 Future after finishing the Special Stage that's close to the end of the level, the same one that the GameXplain guy showed off in his video. So after I returned to the level the controls went completely crazy, the game was playing itself and some actions like jumping and pausing were sporadically disabled, after a few seconds of mashing the pause button I could pause again so I reset the game and loaded up my save file and the issue was still there, but after closing the game completely and reopening it was normal again. This never happened again for the remainder of the game and I have no idea how it happened or how to replicate it, luckily the game auto saves emeralds and lives obtained without requiring to beat an act so no progress was lost, but that was still really strange. Also for some reason Frigid Fortress Past runs really slowly on my computer and I don't know why, considering the rest of the game and even the last two demo versions of that level from SAGE 2014 ran just fine. I also got completely stuck on a floor and a ceiling in Raging Ruins Past and had the restart the game to continue.
Overall though, this was still a really great game, probably my favourite 2D Sonic fan game so far, which I can easily see myself going back to in the future for more playthroughs, after the obligatory Tails and Knuckles runs that I will do later this week of course. Great job.