Really fun game! I played through the whole thing.
-I think the start is pretty slow. Once you get going the pacing is good but at the start you kinda just wait around and do nothing for a bit. Maybe a way to speed up the game could help?
-It would be nice to see if the upgrades unlock something new or not. Sometimes I would get things I don't need just because they may unlock something.
-The hotkeys should stay the same even if you don't have an active skill. If you're doing things fast and you get a new potion/heroic strike it can be annoying
Overall pretty good, I'm looking forward to seeing more levels