This is a fun tower defence game base, however there's nothing to prevent the player from just repeatedly rerolling the dice to get as much currency as they want. I was fairly easily able to fill the entire level with tier 3 towers doing that, maybe have it tied to enemy death instead? The other nice quality of life improvement would be the ability to skip to the next wave when all the enemies are dead. Still, all in all, nice work, especially for the time frame!