Really polished visuals and sounds. I love how fun it is for how simple the concept is.
The 3rd boss felt like the most epic Simon game of my life.
I did run into an unexpected bug not mentionned in the "known issue" part of the description tho :
After dying to the first boss and try to go fight it again, I ended up not having control of my character and the boss stayed in the same state as when it killed me. I had to restart the game (playing on web).