Hi :)
The lighting really gives a great atmosphere and the mining etc. feels good. So, well done.
I think it would be nice if you could always see the castle. maybe in a small window on the top right. I kept going down to mine wax and suddenly I lost... I did not see it coming and that felt weird.
However it was still a fun challenge for me so I tried it a few times. I survived 5 minutes.
It might also be interesting to add some time goals with rewards. So after surviving for 5 min you get 200 wax or something. At 4:30 it just felt hopeless.
I think enemy and tower variety are not super important tbh. I only got to build one cannon and I still think it might have been better to go for wall + tower... So of course you can try to balance this but I think by adding more you would just waste your effort on something that no player will ever use/see.
For anyone except the author reading this: This game is nice so if you are trying to find something to play and rate, this is it. ;)