A game over manager that is responsible for showing the game over UI and handling game restart.

GameOverManager.cs

// Author: themehrankhan

using UnityEngine;
using UnityEngine.SceneManagement;

/// <summary>
/// A game over manager that is responsible for showing the game over UI and handling game restart.
///
/// This manager can be used to centralize the game's game over logic, making it easier to maintain and update.
///
/// To use the game over manager, simply attach this script to a game object in your scene.
/// You can then access the game over manager instance from anywhere in your code using the
/// `GameOverManager.Instance` property.
///
/// To show the game over UI and pause the game, call the `GameOver()` method.
///
/// To restart the game, call the `RestartGame()` method.
/// </summary>
public class GameOverManager : MonoBehaviour
{
    /// <summary>
    /// The singleton instance of the game over manager.
    /// </summary>
    public static GameOverManager Instance { get; private set; }

    /// <summary>
    /// The game over UI object.
    /// </summary>
    public GameObject gameOverUI;

    private void Awake()
    {
        // If there is already a game over manager instance, destroy this instance.
        if (Instance != null)
        {
            Destroy(this);
            return;
        }

        // Set the singleton instance of the game over manager.
        Instance = this;
    }

    /// <summary>
    /// Shows the game over UI and pauses the game.
    /// </summary>
    public void GameOver()
    {
        // Show game over UI
        gameOverUI.SetActive(true);

        // Pause the game
        Time.timeScale = 0f;
    }

    /// <summary>
    /// Reloads the current scene and restarts the game.
    /// </summary>
    public void RestartGame()
    {
        // Reload the current scene
        SceneManager.LoadScene(SceneManager.GetActiveScene().buildIndex);
    }
}