Works best when you log on to your pc , and do all the things in the "free apps" tab.

Basically, all you have to do is enter your email, and a free app will be sent in your inbox. Download the app from the link and after downloaded, play the app for about 1-2 min. Go back to graal and you should have your gralats. Few of the apps dont work either, but most of them work. That's basically how i earn free gralats when it comes to times like when nexus opens, etc.