Cool to see a strategy game here, I actually was originally planning to make something similar, but decided not to since I didn't have a lot of time left after I finished making my engine.
The game crashed for me on level 2, but I liked the mechanics. I don't know if this was intentional, but you can actually just mash the attack button until the enemy dies without having to end your turn. That obviously breaks the "strategy" aspect since it's completely overpowered, but I think it would actually work as a cool mechanic if you tweak it.
For example, maybe you get X action points per turn, and you can decide to spend those on movement or on multiple attacks. That way, you get a defensive advantage (more attacks) by not moving. Attackers will always be at a disadvantage like that though, so some more thought will need to go into it.
Anyways, nice entry. I hope you iron out the issues and release a more complete version!