I’ve also been thinking about how, if you have a good start, it can sometimes be very easy to cut the legs out from underneath the zombies before they really get a chance to grow, making the rest of the game very easy.
On your side, you are growing your gold and mana economy by expanding and capturing towns, and on the zombie side they are expanding and blighting towns and leaving graves full of undead.
I think the problem is that it’s very easy for you to just walk over and burn the zombies graves.
Here is a radical idea, how would the game change if there was no such thing as burning graves and instead, when a town fell, everybody is a zombie instantly. They would not start moving around right away, instead they would send out little groups in exactly the same way as they do now, but in order to “burn the grave” you would need to fight all 500 of the zombies!