You weren't kidding when you said EXTREME!!!
That was pretty fun!! Super intense gameplay when the music kicks up into high gear. The lightning attack is cool!
I think my only request would be to have keyboard select for the upgrades - having to take my hands off the arrow keys to click would leave me vulnerable for a second when I was getting back to the arrow keys.
Took me more than a few tries, but I DID IT!! The only real strategy was maxing damage every time, then getting full heals at the end last few rounds -- because it was impossible to dodge sometimes when the screen was full. Fun game!!