One of the best "couch games"
This game is simply brilliant. To start with, I already love music/rythm/bullet hell games and with the option to add your own music, I know it's going to be superb. This game did it and it did it well, but with a few minor things that didn't work so good. One of those things is the audio quality after the level generation, I hear the quality go down about 30%. You can fix this by lowering the in-game music by ~50% and boosting your main volume a bit. Also the hit box isn't as good as it is in, for example Touhou.
I love the fact that I can just lay on my couch, put on my headphones and relax with some smooth jazz, or liquid dnb. I will surely play this game for many hours. I recommend this game to anyone who likes the Touhou series and bullet hell games.
I give this game a solid 9/10 for the relaxing theme that it has and then again, the crazy bullet hell aspect which just adds up to the experience. It is surely worth the 4€ I paid. Sorry for my grammar and have a good one!