Tried this out with a friend cause the graphics looked really pretty. The backgrounds are colorful and have a nice color palette. I'm familiar with the musician RRThief and his music is pleasant here as well.
I've played some Sonic games before (1-3+K, CD, Mania) but I can't say I'm super into them, so maybe my opinion isn't all the good, but I found the levels sort of a clusterfuck. I just felt like I was being bounced around constantly and bombarded by random enemies. I wasn't really sure where I was going or taking in anything or wanting to explore. As pretty as the levels look on their own they don't read that well. I got to the end boss of the second level, the looney dude guy, and died about 6-7 times before quitting. Having to get up close to a target that spams projectiles is a bit too much for me.
I also find the dialogue and cutscene art a little weird? I'm fine if a game isn't taking itself seriously and this is a test and all, I was bit let down cause the rest of the art style seemed polished. The humor isn't my cup of tea, so I don't know if that's planned for whatever future project it is.
There's some other odd issues here and there, like the shoot em vehicle getting stuck and falling below the camera, but since this says it's a test project, and again is free, I can't pick at it too much. Maybe I just need more time with in the future and could give better constructive feedback, but it feels very rough for myself.