Very smart idea to make the upgrades cheap and the strong turret purchase expensive. Makes you want to use the luck based systems more! The timing is also good on the dice rolls, not too easy, not impossible.
Only thing missing for me was more UI. Seeing the health of enemies, the level of my turret etc. Ofc, I understand the time limitations, but if you want to take it further, I think this is the most missing thing.
It looks very nice, the effects and assets fit the game very well.