First off: thanks for letting me continue even after defeat. Made it easy to see everything.
Impressive to see how many systems you got working in a short time. I also really like the idea of connecting towers to the upgrades, I just wished there was a bit more to it. Maybe that lines couldn't cross so you would need to make specific connections for each tower or something like that. As it is right now, it is just six more clicks to activate an update and no reason not to do it.
But it was still fun to become really overpowered by wave 20. Never saw the boss :)
Great work!