Here is a secret thats not really a secret. This is for all the newbies. When you start the game you can only have 4 stamina points but if you LOG IN TO FACEBOOK VERSION there is a airship and if you click on it you can purchase a 5th stamina point for 25 gems. Also in the facebook version you can try and upgrade a building while your builders are all occupied and you will get a 50% DISCOUNT to get the next BUILDER.