I found the game really fun. I noticed how simple art does not get in the way of the experience when the mechanics have an enjoyable concept behind them.
I felt a little confused about some of the effects that could be collected during the battle. Probably, after playing a few more runs, it would become easier to understand. If you think it makes sense, maybe it would be worth considering a short optional tutorial as the first battle, just showing the first cycle of the mechanics. :)
Congratulations on the work!