Brilliant! I loved this, and had a great time playing it.
Like someone else below, I was a bit confused as to why my buttons sometimes didn't work. Some of that was just because I'd read the controls but didn't have all the upgrades yet, but the other part was that you can't use another skill while one is in progress. Some feedback for when a player tries to do the action but can't would have been nice (also probably for when the skill is still on cooldown).
But anyway, I really enjoyed this (got to round 21, with all the upgrades, though one's cost changed to 1074573526, which is presumably a bug rather than just a high cost). I even went to get my mouse after I struggled around with the trackpad of my laptop for a while, because it's such a nice experience. Great job!