Gem store
This is a fun game however the IAP ruined any chance of true enjoyment. You are given a free mercenary who you are told is weak. To unlock a soldier, you must lease one for two gems or unlock one for 50 gems. A cannon, more gems. I played about 6 quests which were fun, unlocking the soldier and the unit above him (I leased them each time) when the game became very hard. It was pretty obvious that in order to win, you had to buy gems . Although I liked the game to that point, I was not going to pay out of pocket for a soldier when the game is battle based.
Kag 82 about
Battle Towers