Store/modify general game data with gpgs

Hi,

So snapshots are a way of storing the current user’s data in the cloud, which is neat. 

But is there a way of doing the same with any other arbitrary data accessible to all users?

For example, as in messages that are sent to the server and then visible to all other users. Or, displaying total gems collected by all users who have played the game or creating a custom leaderboard etc.