This game plays like the creators stopped developing it and are just making passive income from it. There's no point to the gems after you unlock the skins. The map stops after you conquer the USA. All of the maps are the same, just in different order of obstacles. If you play this for an hour you've experienced the whole game. Shame of a thing, because there is potential here. They couldn't made upgraded units, stronger bosses, larger castles. Instead it's a revolving door.