Bullshit

SELECT u.Username,
       g.Name,
       COUNT(*) AS [Items Count],
       SUM(i.Price) AS [Items Price]
 FROM Games AS g
 INNER JOIN UsersGames AS ug
 ON g.Id = ug.GameId
 INNER JOIN Users AS u
 ON ug.UserId = u.Id
 INNER JOIN UserGameItems AS ugi
 ON ug.Id = ugi.UserGameId
 INNER JOIN Items AS i
 ON ugi.ItemId = i.Id
 GROUP BY u.Username, g.Name
 HAVING COUNT(*) >= 10
 ORDER BY COUNT(*) DESC,
          SUM(i.Price) DESC,
          u.Username ASC