Very nice graphics and gameplay!
It took me a while to understand the mechanics though. But it works well once you figure it out. The only thing that seems to matter in the fight are damage so after a while I just went with saving any red runes and hoping to get 3 or 4 of them to continue the story. I think I only met one boss but it had 1 hp? Killed it in one go. I also got down to level 2 but it was a small empty room. I decided to call it then.
I think the foundation of this game is great and can become a real game with more time put into it. There is some adjustments and balancing to be made. The movement felt good but at times a bit unresponsive if you get impatient for the next input.
The second box at the fight screen was hard to understand as well. I guess it is an additional multiplier that's always added.
Also having the ESC key close the game caught me off guards. I was looking for a menu but exited the game unknowingly. Have this open a close panel or menu. EDIT: I pressed ESC again and noticed there is a menu that pops up for a brief second but the the game exits directly.
All in all I really enjoyed the game!
Good Job!