The trouble I had for my game. which is a turn base battle game. is math and having to calculate over and over how much experience a enemy gives and how much damage one of them does for a move and the level to make everything balanced.
not sure how you went about it, but a way to simplify things could be by using curves to determine the scale/growth of the experience drops and the damage/stats, it's still in the end math but you could find it easier since you have some sort of visualization of the growth (I haven't gotten to do this myself but it is something I am looking into just sharing thoughts)