Now it is possible to connect your Game Network (Game Center or Play Services) account to your Fun Run 2 account. This makes it easier for you to login on different devices, and you'll get achievements on your Game Network account.
New users will be automatically connected to your Game Network, but you can manually connect your Fun Run 2 account to your Game Network account in the settings screen.
For Android users:
In Google Play Games, you can even record your races with your reaction!