And it will work across all platforms?
Like, e.g. someone is playing on desktop and someone else on mobiles and they both see the same leaderboard?
Yes, it will. It works like this: each player can submit its score (with an AJAX call) to a server. All the AJAX POSTs go to the same server and are stored in the same database, no matter if it was posted from a mobile device or from a PC. When you display the leaderboard, you get the metadata from your server with an AJAX GET Request, and the same data is sended to all devices (no matter if desktop or mobile).
Are you familiar with servers and databases (PHP, SQL, etc.)? If not, don't worry. I didn't even know what a server was when I did this. If you need help, just ask.
Sadly, I just tried you hosting and it gave me:
[quote:njm9oz8i]Public registration was temporarily disabled! If you need an account, please contact us using .
Hmm... Try to contact them, they usually answer within 24h.