Hi!
It seems that I didn't have time to kill some enemy and then maybe level 13 is the final one?
From the beginning, I didn't really understand what was going on, but when I was finally able to see the opponents in the form of grass, everything fell into place :).
A good system of sword upgrades with each level. Basically, I invested in strength. Also, the sound is sufficient to complement the gameplay.
Overall I enjoyed everything and had fun swinging the sword, congratulations!