Loved this entry! Great work! Trying to leave the tab long enough to write this. Both fun to get beyond the initial set up before you run out of HP as well as customize the performance with the variety of different lvl1-4 forms. As with other commenters, I look forward to added variety in future releases post jam.
Wave progress indication would be nice, as well as the ability to buy amps without interrupting the game view though I suppose those moments of panic did add to the fun :) I like repetitive music loops, so I have to admit that part didn't bother me. I love the synth mechanic!