I know it is possible,
For example, if I wanted to save a leaderstat, how would I save the value across different games?
I'm not looking for free answers, simply a method or a place to get started.
Universes
What he said
Stick all of the places into the same Universe, and you can use DataStores in all places within the same universe. In the event that you're not going to stick them in the same Universe, you'll need an external service which you can access through HttpService.