LeaderboardManager.cs

using System.Collections;
using System.Collections.Generic;
using GooglePlayGames;
using GooglePlayGames.BasicApi;
using UnityEngine;
using UnityEngine.SocialPlatforms;

public class LeaderboardManager : MonoBehaviour {
	private void SetInteractionEnabled (bool value) {
		//TODO: Add logic here that disables everything you don't want the user to interact with while the leaderboard is open.
	}

	public void AttemptToDisplayLeaderboard () {
		if (!Social.localUser.authenticated) {
			SetInteractionEnabled (false);

			Social.localUser.Authenticate ((bool success) => {
				if (success) {
					DisplayLeaderboard ();
				} else {
					SetInteractionEnabled (true);
				}
			});
		} else {
			SetInteractionEnabled (false);
			DisplayLeaderboard ();
		}
	}

	//Get this value from GPGSIds.
	//e.g. leaderboardID = GPGSIds.leaderboard_leaders;
	private string leaderboardID = "leaderboardID";

	//LeaderboardScoreData will start at rank #1.
	private LeaderboardStart leaderboardStart = LeaderboardStart.TopScores;

	//LeaderboardScoreData will return 100 scores. 
	private int scoresToDisplay = 100;

	//LeaderboardScoreData will be public.
	private LeaderboardCollection leaderboardType = LeaderboardCollection.Public;

	//LeaderboardScoreData will show all time scores.
	private LeaderboardTimeSpan leaderboardTimeSpan = LeaderboardTimeSpan.AllTime;

	private void DisplayLeaderboard () {
		PlayGamesPlatform.Instance.LoadScores (leaderboardID,
			leaderboardStart,
			scoresToDisplay,
			leaderboardType,
			leaderboardTimeSpan,
			(LeaderboardScoreData data) => {
				//List of userIDs that we're going to use to retrieve usernames.
				List<string> userIDs = new List<string> ();

				//Map of userIDs to their related score.
				Dictionary<string, IScore> userScores = new Dictionary<string, IScore> ();
				for (int i = 0; i < data.Scores.Length; i++) {
					IScore score = data.Scores[i];
					userIDs.Add (score.userID);
					userScores[score.userID] = score;
				}

				//Map of userIDs to their usernames.
				Dictionary<string, string> userNames = new Dictionary<string, string> ();
				Social.LoadUsers (userIDs.ToArray (), (users) => {
					for (int i = 0; i < users.Length; i++) {
						userNames[users[i].id] = users[i].userName;
					}

					//The reason we loop through data.Scores here is the same reason we created the two dictionaries above.
					//[data.Scores] is guaranteed to be in the correct order while [users] is not.
					for (int i = 0; i < data.Scores.Length; i++) {
						IScore score = data.Scores[i];

						//This gets the imageIndex that can be used to grab an image from an array or dictionary.
						//e.g. Sprite image = leaderboardSprites[imageIndex];
						int imageIndex = (int) (score.value % imageIndexMax);

						string userName = userNames[score.userID];
						int rank = score.rank;

						//This removes the imageIndex from the score to get the true score.
						float scoreValue = ((score.value - imageIndex) / imageIndexMax);
						
						//TODO: Use the values above to update a display in Unity.
					}
				});
			});
	}

	//Score: The score you want to display on the leaderboard.
	//ImageIndex: The index for which image you want to display on the leaderboard.

	//I have around 212 unique images that I want to be able to display on my leaderboard. 
	//In order to add that index to my score I'll need add at least three trailing zeroes to my score.
	private float imageIndexMax = 1000;

	//Multiply the true score by imageIndexMax, add the imageIndex, and then report that new score.
	//To display the image, parse the imageIndex when DisplayLeaderboard (on Line 46) is called.
	public void ReportScoreToLeaderboard (float score, int imageIndex) {
		long leaderboardScore = (long) (score * imageIndexMax + imageIndex);
		Social.ReportScore (leaderboardScore, leaderboardID, (bool success) => {
			Debug.Log ("Success!");
		});
	}
}

maybe all things will be better if you provide the complete source code