Unlike @OneThousandMeeps below me I actually had to complete the last level to get the last medal. Man was it rough. Just the last level itself took me about 2 weeks! But... man... I liked this game. I actually think it's one of your best idle games. I have all of the medals on almost all of your games, but I never worked so hard in an idle game for a single medal.
I thought the balance was good throughout the game. It was interesting seeing the different towns and enemy make ups.
The only thing that I can think to make this game better is a way to know which unit does what to each enemy. That being said, it's really not necessary because by the last level I had every single thing maxed out anyway. Perhaps some way of extending the research for the mages? Once that was maxed it, which I focused on early on, there wasn't much more to do other than to wait for my army to be maxed out and send them again.
Anyways, I really enjoyed this one. It literally took me about a month of gameplay to get through the whole thing. It really takes commitment!