First off, I have been playing this game a lot over the past few days, and I am having fun with it. However, as most posts will also share my opinion, it seems to have no adhesiveness to it. In other words, no boundaries or limitations. I mainly speak of the item stacking, as others have pointed out as well.
Stacking attack and defense and easily winning the game is one thing, but in my opinion, there is a much larger game changer if this ever does go multi-player. I am talking about the Band of the Eagle Eye. It takes very little to unlock this ring, which gives +1 sight when equipped and only costs 10 Gildar per ring. I am playing a game at the moment and started at the very top (North if the map was turned directionally). So i decided to see how many rings it would take to unlock the entire map by staying inside the starting city. The total was 137, which allowed me to see every single thing on the map, including what kind of troops were guarding the enemy towns. So, if one were inclined, they could go straight to the tech that unlocks the ring and only spend 1370 Gildar (even less I bet depending on where you start on the map) to map out a plan to win the game. Of course this would lead to everyone doing it, so it would change the face of the strategy altogether.
I'm not a programmer, so I won't pretend to know the best avenue, but something like this could definitely be a game breaker. please consider limiting the equippable items. To me, it doesn't matter if it's realistic or not, as long as it isn't overpowered and a must in every game.