Nice work! A nicely polished game! I enjoyed it!
I have some feedback about the dice mechanic, I like how it dictates how much money you have to spend but my cash went negative multiple times and I couldn't crawl out of it.
What if the dice was a multiplier that increased your cash but upgrades got more expensive? It would let the player interact with the game more because having negative cash doesn't let you interact with the game enough.
It would also be cool if the enemy tower had its own stats that changed, so then player would have to choose upgrades based on the enemy towers stat increases.
Take my feedback with a grain of salt because I know these suggestions are probably outside the scope of the jam! The game I made for the jam is actually somewhat similar I really like this concept.
You made an awesome game that you should be proud of!