There is a question mark section in the bottom of main screen. You can tap on that and app will enter into explanation mode. We only need to follow that screen explanation steps in order to understand how it works. You could also do some playground tries on the same screen. *

Menu bar appears after we tap on gear icon. In it we can locate Game Center, Languages, Rate App and the bonus image. The last one indicates your bonus's state, which is changed by playing hard, you can use that to gain more points and signs for further play.

In case you have burned all of your signs during play you still have two ways of getting new ones - first by making a purchase; go to the main screen and tap on purchase icon, second by using the bonus.

Simply never, you can always compete while gaining more scores again and again