Decent idle game, except when you have to upgrade the building. Need RNG acquired materials to get coins to progress, and that RNG only progresses while the app is open. Doesn't matter how well you manage the production, or how much money you make. You are still bound by the luck of the draw to "produce" minimal amounts of required material every 3 minutes, while leaving the app open. Make the materials a guaranteed choice, and its a 5 star game. Im done sitting for 4 hrs and not getting nails.