I liked the game, it was pretty difficult.
The music is really good and the art looks pretty nice. My only problem with the visuals is the background, the rings sometimes become extremely fast and it just hurts my eyes.
The gameplay is very fun and addictive, I always wanted to play more. I did have one problem, there was a delay of pressing the button and the portal spawning (maybe because I am using Microsoft Edge), it made the game even harder.
Overall I liked it, I'm probably going to play some more.