Really nice idea
What would be some very nice improvements are:
1- Audio, this would make a lot
2- Maybe some information about the power ups (You can add them on the description of the page for example)
3- Some combat reactions, like blinking or moving on attack, really important to have this feeling of something happening.
Nice job, the idea is very good, and you did everything from scratch.
If you have some time, I would love to have your feedback on our game also