This was quite fun, took me about 3-4 tries but I eventually beat it, it looks like there is no penalty if you can’t sustain your factories, so I just saved up and bought everything at once, allowing me to have 2-3 extra factories in place of what would normally be a bank.
The sudden turn to tower defense was a nice surprise, although I partially suspected it due to the health bar, if you’re aiming for having as big a surprise as possible then hiding it until the building takes damage might help
Not sure how hard your artist worked but if they were lazing around toward the end of things it would have been neat if they drew up a defrosted version of the map to show after winning the game.
Nice work!