You can load Json strings into a dictionnary object, which can be displayed later, I think the Json string must be written in a certain way (for C2 to understand it is a dictionnary), I can try to found it if you want.
1/EDIT, the Json File you have should contain:
{"c2dictionary":true,"data":{"game":"10"},{"user":"1"},{"score":"1000"}}
or simply, you get your actual file, and add the {"c2dictionary":true,"data": and teh last } later
2/To load the Json, is it a file in C2, or hosted on a server(the AJAX object can use a GET request to get a Json file from a server If I remember)?