Thanks for the feedback!
Yeah, I'm really bummed that it shipped with two pretty big bugs (tower 2 and 3 not upgradable, upgrades past level 7 result in crash). I did post a version with bug fixes (but no new content or improvements, to stick with the spirit of the jam). Without the additional mechanics I had planned to implement, it is a bit repetitive though.
Although it was rough, I don't regret picking up pico8. I had a ton of fun with it, and the limitations were exciting to overcome. This was my first jam, so I underestimated how fast the end would come, and the fact the I would actually need sleep during the 48 hrs. lol