I got insta-killed in round 3 lol. The building mechanics is interesting. The problem is the cost of connectors to chain between buildings are almost the same as weapon buildings so you end up having to wait another wave to activate a weapon building. I can only buy 1 or nothing after each wave as money reward seems to be pre-determined per wave. Not sure, I may be doing it wrong. I will give it a try later, I got demotivated after several attempts of losing fast. My skill issue.
The low-res pixel art is charming and consistent so very good on that. The explosion particles are too many and some too huge, and at first I mistook the yellow ones are coins to grab lol. Retro soundtrack and retro sounds is a good decision. Overall I think you did great.