Thank you sooo much
As for difficulty, I made it really hard because I enjoy harder games and because it's short, 6 levels + boss, but thanks for suggestion.
Also you heal 10% of you max HP at every start of a new level, and there is artifact called "Restore UP" which add 10% more to your healing at the start of every level, though I guess it's not a lot.
Thank you very much for playing, I really appreciate it