Spark's pretty neat. It does all of the things Sonic can't seem to pull off even tho Sonic Team being an enormous team. Mainly, it convinced me that the Sonic formula of Adventure actually can work.

I technically didn't finish it, because I died in the last level after 20 minutes, because the game taught me earlier not to dash on walls, as dashing during the speed passages on walls normally disconnects you from the floor, so I didn't try when the game expected it from me and I'm not really willing to replay these 20 minutes of gameplay, because the dev thought it would be a good idea to introduce a life-system just for that one level. I fundamentally disagree with his design-philosophy here, it doesn't serve anything other than frustration should you run out of lives, in a game that doesn't have them in literally any other level.

Before that tho, the game's really fun and has great levels it's fun to speed-run actually. The combat is brainless mostly, but better than what Sonic Frontiers cooked up last year and as this is a direct Sonic fan game I will excuse the comparison here and I hope you do too.
Soundtrack goes REALLY hard and the overall presentation works pretty well too.
It this goes on sale and you like speed-based platformers, I highly recommend this to you.