Angry Birds in Unity

using UnityEngine;

public class PigsManager : MonoBehaviour
{
    GameManager gameManager;
    UIManager uiManager;

    int pigsTotal;
    int pigsDestroyed = 0;

    void Start()
    {
        gameManager = FindObjectOfType<GameManager>();
        uiManager = FindObjectOfType<UIManager>();
        pigsTotal = transform.childCount;

        if (uiManager != null)
        {
            uiManager.UpdatePigStats(pigsDestroyed, pigsTotal);
        }
    }

    public void RegisterPigDestroy()
    {
        pigsDestroyed++;
        
        if(uiManager != null)
        {
            uiManager.UpdatePigStats(pigsDestroyed, pigsTotal);
        }


        if(pigsDestroyed == pigsTotal)
        {
            if(gameManager != null)
            {
                gameManager.SwitchScene();
            }
        }
    }
}

using UnityEngine;

public class Pig : MonoBehaviour
{
    private void OnCollisionEnter2D(Collision2D collision)
    {
        if (collision.transform.CompareTag("Ground"))
        {
            GetComponentInParent<PigsManager>().RegisterPigDestroy();
            Destroy(gameObject);
        }
    }
}

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Player : MonoBehaviour
{
    [SerializeField] float force = 5f;
    [SerializeField] Transform pivot;

    Camera cam;
    Rigidbody2D rb;
    LineRenderer lineRenderer;

    Vector3 tempPos;
    Vector3 dir;
    Vector3 startPos;
    bool canBeMoved = true;

    void Awake()
    {
        rb = GetComponent<Rigidbody2D>();
        lineRenderer = GetComponent<LineRenderer>();
    }
    void Start()
    {
        cam = Camera.main;
        startPos = transform.position;
        lineRenderer.SetPosition(0, pivot.position);
        lineRenderer.SetPosition(1, transform.position);
        RotatePlayer();
    }

    private void Update()
    {
        if(Input.GetMouseButtonDown(1))
        {
            ResetPlayer();
        }
    }

    private void OnMouseDrag()
    {
        if (canBeMoved)
        {
            tempPos = cam.ScreenToWorldPoint(Input.mousePosition);
            tempPos.z = 0f;
            
            if(tempPos.x < pivot.position.x)
            {
                transform.position = tempPos;
            }
            dir = pivot.position - transform.position;
            lineRenderer.SetPosition(1, transform.position);
            RotatePlayer();
        }
    }

    private void OnMouseUp()
    {
        if (canBeMoved)
        {
            rb.gravityScale = 1f;
            rb.AddForce(dir * force, ForceMode2D.Impulse);
            canBeMoved = false;
            lineRenderer.SetPosition(1, pivot.position);
        }
    }

    void ResetPlayer()
    {
        rb.gravityScale = 0f;
        rb.velocity = Vector3.zero;
        rb.angularVelocity = 0f;
        transform.position = startPos;
        canBeMoved = true;
        lineRenderer.SetPosition(1, transform.position);
        RotatePlayer();
    }

    void RotatePlayer()
    {
        Vector3 diff = transform.position - pivot.position;
        diff.Normalize();
        float rotZ = Mathf.Atan2(diff.y, diff.x) * Mathf.Rad2Deg;
        transform.localRotation = Quaternion.Euler(0f, 0f, rotZ + 90f);
    }

}

using UnityEngine;
using UnityEngine.SceneManagement;

public class GameManager : MonoBehaviour
{
    int activeSceneNumber;
    int scenesTotal;
    void Start()
    {
        activeSceneNumber = SceneManager.GetActiveScene().buildIndex;
        scenesTotal = SceneManager.sceneCountInBuildSettings;
    }

    public void SwitchScene()
    {
        if (activeSceneNumber + 1 < scenesTotal)
        {
            SceneManager.LoadScene(++activeSceneNumber);
        }
        else
        {
            SceneManager.LoadScene(0);
        }
    }
}

using UnityEngine;
using TMPro;

public class UIManager : MonoBehaviour
{
    [SerializeField] TMP_Text txtPigsStats;

    public void UpdatePigStats(int pigsDestroyed, int pigsTotal)
    {
        txtPigsStats.text = $"{pigsDestroyed} / {pigsTotal}";
    }
}