Playing through MOST (I think) of the second half of an apparently recently recovered 2022 build--version 1.6.16--of unfinished Sonic fan game Sonic Classic 2, by @HezMan2000 .
It becomes clear in the second half that this is still very much a work-in-progress as the stages do start to get rougher and rougher, with more and more cheap deaths (hopefully these are things the author is still working on and not how they think they have to ramp up difficulty!); Flying Fortress Zone doesn't have the game's usual meticulously parallaxed layer upon layer of gorgeous pixel art background detail, and dumps you right into a big pit that does not feel like the start of a level; and the final or some final boss fight anyway lurches very slowly through a cycle of clunky attack patterns, that aren't actually very dangerous because a glitch lets you keep re-activating your shield--but once in a while it does a sorta insta-kill attack and bah, I couldn't deal.
So hopefully this stuff IS still being worked on, along with the meandering performance level and so forth. I'm following the author on YT so I'll just have to check in every once in a...while. ^ _^