Just came across this game and it's great! It has a good feel to it, only a few minor annoyances with regards to some added mechanics, but they can be disabled. Regardless, I finished the game as-is.
It's a great mix between the original 8bit levels revisited and demakes of 16bit levels. It always felt right. I grew up with the 16bit Sonic and the 8bit Game Gear version.
My only big grievance is that the second jungle level uses the SMS version of not being able to scroll back down. It would not be an issue if the game didn't keep prematurely scrolling upwards when you jump. It leaves you nowhere to land, and touching the bottom edge kills you. I lost the most lives on this level. The GG version didn't have this, you could fall back down to a lower part of the level.
Lots of playable characters, like Tails, Knuckles and Fang. They can have their own paths in the levels that Sonic can't reach. You can become Super Sonic. Great experience all around.
Besides having replayability (time attack, encore, playing with other characters, ...) there is also a Sonic SMS Remake 2 and 3, will be playing these next.
Played on my Odroid GO Ultra running Rocknix and portmaster.
I rate this 9/10.
https://sonic-sms-remake.blogspot.com/
The mechanic annoyances were the drop dash activating unintended, sending you off edges to your death, and the stopping animation where Sonic "brakes" with his feet interfering with movement while jumping. It prevents you from accelerating during the jump. This happens a lot on narrow platforms where you jump on, correct your direction not to fall off, then jumping to the next one only to realize there's no velocity gain in the direction you're now trying to go. Fell a lot to my death with this one. I don't even think you can correct the direction while in the air this way.