I got up to level three, I don't know what else is after that.
I like the visual style and sound effects, they fit and work. I also like each unique hero and how they all play differently. (Don't know what the wizard is supposed to do, the explosion ring is really weak.)
Without a tutorial, though, some things are confusing, though. The first thing I see is a list of like 200 items with attributes I don't understand. That's probably for debug though.
The other thing that confuses me is the entire lose state. On level 3 it says 1/0 so I don't think it's that. In the first 2 levels I could have all heroes on the board and not lose, and sometimes I lose when a hero dies, and sometimes it's fine.
My suggestion is to tie it all to hero health, and have recalling damage the hero. If all heroes are dead, the round is lost. Right now, health doesn't seem to do much as heroes don't attack even if left on the board.
Also the cannon sounds like a bird when moving.