Leaderboard には特定のゲームに関する全プレイヤーのスコアのデータが含まれています。
Each game can have multiple leaderboards with different scores. A leaderboard object can be customized to perform a particular query. The leaderboard ID defines which leaderboard is being queried and there are filters to narrow down the results, UserScope, TimeScope, Range and SetUserFilter. Use Social.CreateLeaderboard to create an instance of this object.