Yeah it ended up be too easy. The whole game didn't really come together until the last couple of days and we were doing lots of fixes up until the end. We never got a good look at the balance and wanted to make sure it wasn't impossible so tried to lean to the easier side.
I personally don't think it should be balanced around the dice you have. It don't like games that scale difficulty to you as it means you never really feel like you are improving. Upgrades become meaningless if every upgrade you buy the boss would upgrade as well. It really just needed a lot higher scaling in difficulty, more exponential than it already is.
Also after playtesting it more and more I think the upgrades should be limited. I originally wanted multiple types of upgrades and then you could only have one of each type applied to a dice. That way you couldn't just keep doubling the sides of one die over and over. But alas time limits hit and things were cut.
Glad you had fun playing it though!