Thanks for this feedback.
Mana recovery from channeling elements is not obvious enough, everyone so far has missed it. I'm definitely going to make a better visual.
The demo's progression is just gradually scaling parameters over time right now. It's a testing environment for the real game mode (longer campaign of level-choosing on a map etc), so I appreciate the balance feedback + progression suggestions to specifically improve it.
Also, there is no 3-element combination. It seems to be heavily implied by the visuals but I don't intend for that, I have to work on it. The player is meant to have two unique spells equipped always, but incentivized to flip between elements for other spells or just mana.