Meh
It's a very nice game, and I've been playing this one on my old phone. But maybe you should consider increasing the amount of gold in every flight and every task. It's so hard to save up for the next level because the amount was too expensive. For example, the extension of land. It costs too much but you're giving only hundreds of gold for every flight accomplished. How can we save up for hundreds of thousands for the extension if your giving only few golds.