This was a lovely distraction for in-between daily chores. I made it almost up to wave 50, when I noticed that a single shock tower is capable of holding back almost anything :D
Aside from that slight balancing issue, this has a great core gameplay loop. Just keeping the towers refuled seems to actually be enough to keep you mentally occupied for quite some time!
Just needs a pause-button to stretch your fingers sometimes, and maybe add controller button mappings (movement works with controller already, probably because you never turned it off from the defaults :D Just the actions are missing).