Improvements to Unity Endless Runner tutorial from http://catlikecoding.com/unity/tutorials/runner/; Find more information about my version at http://ideascomecheap.blogspot.com/search/label/Unity%20Endless%20Runner%20Tutorial

GameEventManager.cs

public static class GameEventManager {

	public delegate void GameEvent();

	public static event GameEvent GameStart, GameOver,
		GamePause, GameResume;

	public static void TriggerGameStart() {
		if (GameStart != null) {
			GameStart();
		}
	}

	public static void TriggerGameOver() {
		if (GameOver != null) {
			GameOver();
		}
	}

	public static void TriggerGamePause() {
		if (GamePause != null) {
			GamePause();
		}
	}

	public static void TriggerGameResume() {
		if (GameResume != null) {
			GameResume();
		}
	}
}

GameExitManager.cs

// This is a new file that is not mentioned in the tutorial
//
// To use this, create a new empty under manager with this attached
//
// This is created so that Android application can be exited by pressing the back button

using UnityEngine;

public class GameExitManager : MonoBehaviour {

	void Update () {
		if (Input.GetKeyDown("escape")) {
			Application.Quit();
		}
	}
}

GameStateManager.cs

using UnityEngine;

public class GameStateManager : MonoBehaviour {
	enum State { PLAY, PAUSE }

	private State gameState;
	public GUITexture speakerToggleControl;

	void Start() {
		GameEventManager.GameStart += GameStart;
		GameEventManager.GameOver += GameOver;
		GameEventManager.GamePause += GamePause;
		GameEventManager.GameResume += GameResume;
		gameState = State.PLAY;
		enabled = false;
	}

	void Update() {
		if (gameState == State.PLAY && Input.GetKeyDown("escape")) {
			Time.timeScale = 0.0f;
			GameEventManager.TriggerGamePause();
		}
		else if (gameState == State.PAUSE &&
		         (Input.GetButtonDown("Jump") ||
		 			((Application.platform == RuntimePlatform.Android) && (Input.touchCount > 0 &&
		                                                       Input.GetTouch(0).phase == TouchPhase.Began &&
		                                                       !speakerToggleControl.HitTest(Input.GetTouch (0).position))))) {
			Time.timeScale = 1.0f;
			GameEventManager.TriggerGameResume();
		}
		else if (gameState == State.PAUSE && Input.GetKeyDown("escape")) {
			Application.Quit();
		}
	}

	private void GameStart() {
		enabled = true;
	}

	private void GameOver() {
		enabled = false;
	}

	private void GamePause() {
		gameState = State.PAUSE;
	}

	private void GameResume() {
		gameState = State.PLAY;
	}
}

GUIManager.cs

using UnityEngine;
using System;
using System.Collections;

public class GUIManager : MonoBehaviour {

	public GUIText boostsText,
		distanceText,
		gameOverText,
		instructionsText,
		runnerText,
		highScoresText,
		gamePauseText,
		onPauseInstructionsText;
	public GUITexture boostsSign,
		speakerToggleControl,
		highScoresSign;

	private static GUIManager instance;

	void Start() {
		instance = this;
		GameEventManager.GameStart += GameStart;
		GameEventManager.GameOver += GameOver;
		gameOverText.enabled = false;
		// Hans
		boostsText.enabled = false;
		boostsSign.enabled = false;
		distanceText.enabled = false;
		highScoresText.enabled = false;
		highScoresSign.enabled = false;

		GameEventManager.GamePause += GamePause;
		GameEventManager.GameResume += GameResume;
		gamePauseText.enabled = false;
		onPauseInstructionsText.enabled = false;

		if (Application.platform == RuntimePlatform.Android) {
			instructionsText.text = "Tap to play or press back to quit";
			onPauseInstructionsText.text = "Tap to resume or press back to quit";
		}
	}

	void Update() {
		if ((Input.GetButtonDown("Jump")) ||
		    ((Application.platform == RuntimePlatform.Android) && (Input.touchCount > 0 &&
		                                                       Input.GetTouch(0).phase == TouchPhase.Began &&
		                                                       !speakerToggleControl.HitTest(Input.GetTouch(0).position)))) {
			GameEventManager.TriggerGameStart();
		}
		else if (Input.GetKeyDown("escape"))
		{
			Application.Quit();
		}
	}

	private void GameStart() {
		gameOverText.enabled = false;
		instructionsText.enabled = false;
		runnerText.enabled = false;
		highScoresText.enabled = false;
		highScoresSign.enabled = false;

		boostsText.enabled = true;
		boostsSign.enabled = true;
		distanceText.enabled = true;

		enabled = false;
	}

	private void GameOver() {
		boostsText.enabled = false;
		boostsSign.enabled = false;
		distanceText.enabled = false;

		gameOverText.enabled = true;
		instructionsText.enabled = true;
		highScoresText.enabled = true;
		highScoresSign.enabled = true;

		enabled = true;
	}

	private void GamePause() {
		gamePauseText.enabled = true;
		onPauseInstructionsText.enabled = true;
	}

	private void GameResume() {
		gamePauseText.enabled = false;
		onPauseInstructionsText.enabled = false;
	}

	public static void SetBoosts(int boosts) {
		instance.boostsText.text = boosts.ToString();
	}

	public static void SetDistance(float distance) {
		instance.distanceText.text = distance.ToString("f0");
	}

	public static void SetHighScoreBoard(ArrayList highScores) {
		string highScoreBoard = "High Scores";

		for (int i = 0; i < highScores.Count; i++) {
			highScoreBoard += "\n";
			highScoreBoard += (i+1).ToString() + ". ";
			highScoreBoard += highScores[i].ToString();
		}

		instance.highScoresText.text = highScoreBoard;
		Rect highScoresTextSize = instance.highScoresText.GetScreenRect();
		//print(highScoresTextSize);
		float highScoresSignWidth = highScoresTextSize.width + 60;
		float highScoresSignHeight = highScoresTextSize.height + 40;
		// The object position in the scene (x = 0.5, y = 0.9) will be the reference for the rect.
		// These position will be treated as 0 of left and top. x goes from left to right and y from top to bottom.
		// Hence, the left will be width/2, while top will be height (since the object pivot is bottom left -
		// try setting both left and top as 0 to see this) substracted by half of padding (40/2 as of above).
		float highScoresSignLeft = -1 * highScoresSignWidth/2;
		float highScoresSignTop = -1 * highScoresTextSize.height - 20;
		instance.highScoresSign.guiTexture.pixelInset = new Rect(highScoresSignLeft,
		                                                         highScoresSignTop,
		                                                         highScoresSignWidth,
		                                                         highScoresSignHeight);
	}
}

HighScoreSaveLoadManager.cs

using UnityEngine;
using System;
using System.Collections;

public class HighScoreSaveLoadManager : MonoBehaviour {
	public int noOfHighScores;

	private ArrayList highScores = new ArrayList();

	private static HighScoreSaveLoadManager instance;

	void Start () {
		instance = this;

		LoadHighScore();
	}

	public static int GetHighScoresQuota() {
		return instance.noOfHighScores;
	}

	public static ArrayList GetHighScores() {
		return instance.highScores;
	}

	public static void SetHighScores(ArrayList updatedHighScore) {
		instance.highScores = updatedHighScore;
		SaveHighScore();
	}

	private static void SaveHighScore() {

		for (int i = 0; i < instance.highScores.Count; i++) {
			PlayerPrefs.SetInt("HighScore"+i.ToString(), (int) instance.highScores[i]);
		}
	}

	private static void LoadHighScore() {
		ArrayList loadHighScores = new ArrayList();

		int counter = 0;

		while (true) {
			if (PlayerPrefs.HasKey("HighScore"+counter.ToString())) {
				loadHighScores.Add(PlayerPrefs.GetInt("HighScore"+counter.ToString()));
				counter++;
			}
			else {
				break;
			}
		}

		instance.highScores = loadHighScores;
	}
}

Runner.cs

using UnityEngine;
using System;
using System.Collections;

public class Runner : MonoBehaviour {

	public static float distanceTraveled;
	public float acceleration;
	public Vector3 boostVelocity, jumpVelocity;
	public float gameOverY;

	private bool touchingPlatform;
	private Vector3 startPosition;
	private static int boosts;

	void Start() {
		GameEventManager.GameStart += GameStart;
		GameEventManager.GameOver += GameOver;
		GameEventManager.GamePause += GamePause;
		GameEventManager.GameResume += GameResume;
		startPosition = transform.localPosition;
		renderer.enabled = false;
		rigidbody.isKinematic = true;
		enabled = false;
	}

	private void GameStart () {
		boosts = 0;
		GUIManager.SetBoosts(boosts);
		distanceTraveled = 0f;
		GUIManager.SetDistance(distanceTraveled);
		transform.localPosition = startPosition;
		renderer.enabled = true;
		rigidbody.isKinematic = false;
		enabled = true;
	}

	private void GameOver() {
		RecordScoreIfNecessary();

		renderer.enabled = false;
		rigidbody.isKinematic = true;
		enabled = false;
	}

	private void GamePause() {
		enabled = false;
	}

	private void GameResume() {
		enabled = true;
	}

	void Update () {
		if ((Input.GetButtonDown("Jump")) ||
		    ((Application.platform == RuntimePlatform.Android) && (Input.touchCount > 0 && Input.GetTouch(0).phase == TouchPhase.Began))) {
			Jump ();
		}
		distanceTraveled = transform.localPosition.x;
		GUIManager.SetDistance (distanceTraveled);

		if (transform.localPosition.y < gameOverY) {
			GameEventManager.TriggerGameOver();
		}
	}

	void FixedUpdate() {
		if (touchingPlatform) {
			rigidbody.AddForce(acceleration, 0f, 0f, ForceMode.Acceleration);
		}
	}

	void OnCollisionEnter() {
		touchingPlatform = true;
	}

	void OnCollisionExit() {
		touchingPlatform = false;
	}

	public static void AddBoost() {
		boosts += 1;
		GUIManager.SetBoosts(boosts);
	}

	private void Jump() {
		if (touchingPlatform) {
			rigidbody.AddForce(jumpVelocity, ForceMode.VelocityChange);
			touchingPlatform = false; // This allow one jump after colliding with side of platform, but not more
		}
		else if (boosts > 0) {
			rigidbody.AddForce(boostVelocity, ForceMode.VelocityChange);
			boosts -= 1;
			GUIManager.SetBoosts (boosts);
		}
	}

	public void RecordScoreIfNecessary() {
		int roundedScore = (int) Math.Round(distanceTraveled);

		ArrayList highScores = HighScoreSaveLoadManager.GetHighScores();
		int highScoresQuota = HighScoreSaveLoadManager.GetHighScoresQuota();
		
		highScores.Add(roundedScore);
		highScores.Sort();
		highScores.Reverse();
		
		if (highScores.Count > highScoresQuota) {
			highScores.RemoveRange(highScoresQuota, highScores.Count - highScoresQuota);
		}
		
		//		for (int i = 0; i < highScores.Count; i++) {
		//			Debug.Log(highScores[i]);
		//		}

		GUIManager.SetHighScoreBoard(highScores);
		HighScoreSaveLoadManager.SetHighScores(highScores);
	}
}

SpeakerToggleControl.cs

using UnityEngine;
using System.Collections;

public class SpeakerToggleControl : MonoBehaviour {
	private bool soundStatus;
	public Texture speakerOn;
	public Texture speakerOff;

	private enum BgmStatus { OFF = 0, ON = 1};

	void Start() {
		if (PlayerPrefs.HasKey("BgmStatus")) {
			if (PlayerPrefs.GetInt("BgmStatus") == (int) BgmStatus.ON) {
				soundStatus = true;
				SetAudioListener(true);
			}
			else {
				soundStatus = false;
				SetAudioListener(false);
			}
		}
		else {
			soundStatus = true;
			SetAudioListener(true);
			SaveBgmStatus(BgmStatus.ON);
		}

		GameEventManager.GameStart += GameStart;
		GameEventManager.GamePause += GamePause;
		GameEventManager.GameResume += GameResume;
	}

	void OnMouseUp() {
		if (soundStatus)
		{
			SetAudioListener(false);
		}
		else
		{
			SetAudioListener(true);
		}

		soundStatus = !soundStatus;

		SaveBgmStatus(soundStatus);
	}

	void SetAudioListener(bool status) {
		if (status) {
			AudioListener.pause = false;
			AudioListener.volume = 1;
			guiTexture.texture = speakerOn;
		}
		else {
			AudioListener.pause = true;
			AudioListener.volume = 0;
			guiTexture.texture = speakerOff;
		}
	}

	void SaveBgmStatus(bool status) {
		if (status) {
			PlayerPrefs.SetInt("BgmStatus", (int) BgmStatus.ON);
		}
		else {
			PlayerPrefs.SetInt("BgmStatus", (int) BgmStatus.OFF);
		}
	}

	void SaveBgmStatus(BgmStatus status) {
		PlayerPrefs.SetInt("BgmStatus", (int) status);
	}

	void GameStart() {
		guiTexture.enabled = false;
	}

	void GamePause() {
		guiTexture.enabled = true;
	}

	void GameResume() {
		guiTexture.enabled = false;
	}
}

I need this idea...