I liked this game, and once I got into the rougelite/run structure of it, the difficulty curve also started to make sense.
The graphics are simple but effective, with a clear color palette. Though more juice (glow, bounce, intros, outros...) would probably make the game feel cooler still, lots one can do within this general minimalistic style.
I agree with previous comments on information communication... it's not always obvious what upgrades will do... the whole concept of "upgrades" being the word for the in-battle hex modification wasn't obvious to me, since it could also refer to the between-game improvements. And also the state of the game... it felt a bit "amorphous" to me... where it was hard to quickly identify what the important features are. I think this is partly a risk with the minimalist style... that's one of the jobs those big black dragon graphics might do in a fantasy themed game, drawing your eye and make it immediately obvious that you need to focus on them. I think your game might need to solve that same problem in some other way.
Is there a way to do upgrades et al without using the keyboard shortcuts? Because I think there should be, even if it's suboptimal for an actions-per-second PoV.
All-in-all though, this is a game with clear potential... might need improvements in the presentation, and more features, to make it feel more like a complete package, but I believe the bones are there and work well! I had fun while playing it, and that's a very good start.