As indicated already in our Forum and in our community, Miniclip strongly suggests upgrading any Guest account to avoid any data loss. Why?
Imagine the following scenario:
There you are, shooting hoops in your favorite basketball game, Basketball Stars, when you lose your Guest Account! Oh no, that's not good. What now?
In most of the cases, there is no way for us to recover your Guest Account, so it's lost forever. But fear not, if you link your game to a Facebook account, you'll be safe.
How can you link your account?
If you access your settings, you'll see a small "Login" icon. By clicking it, you'll link your account to the Facebook account that is logged-in in the device.
That's it, the account is now saved. Enjoy your game!