I'm planning to add a shop were you and perches items you can also unlock more active abilities as time goes on. After the first world is unlocked you also unlock an additional unit and a much higher gold rate adding a bit more depth to what you purchase and were you can use your money as each unit has its own equipment tree. The idea is that you set your units up for the battle and then send them out. As this is still very early development there is a bit less to do between waves than there will be.