Unity Scripts: For 2D Monster Chase Game

Create a simple Monster Chase 2D game using Unity C#. It includes backgrounds, monsters, and players to create a game environment where scripting for player movement and collision detection is done:

• Player
• CameraFollow
• Collector
• Monster
• GameManager
• GameplayUIController
• MainMenuController
• MonsterSpawner

Monster Chase

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

public class Player : MonoBehaviour
{
    [SerializeField] // SerializeField forces the private variable property to only on inspectar tab
    private float moveForce = 10f;

    [SerializeField]
    private float jumpForce = 11f;

    private float movementX;

    private Rigidbody2D myBody;

    private SpriteRenderer sr;

    private Animator anim;
    private string WALK_ANIMATION = "Walk";

    private bool isGrounded;
    private string Ground_TAG = "Ground";

    private string ENEMY_TAG = "Enemy";

    private void Awake()
    {
        myBody = GetComponent<Rigidbody2D>();
        anim = GetComponent<Animator>();
        sr = GetComponent<SpriteRenderer>();
    }

    void Update()
    {
        PlayerMoveKeyboard();
        AnimatePlayer();
        PlayerJump();
    }

    void PlayerMoveKeyboard()
    {
        movementX = Input.GetAxisRaw("Horizontal");

        transform.position += new Vector3(movementX, 0f, 0f) * Time.deltaTime * moveForce;
    }

    void AnimatePlayer()
    {
        if (movementX > 0)
        {
            // Player Right Movement & Animation
            anim.SetBool(WALK_ANIMATION, true);
            sr.flipX = false;

        } else if (movementX < 0)
        {
            // Player Left Movement & Animation
            anim.SetBool(WALK_ANIMATION, true);
            sr.flipX = true;
        } else
        {
            // Player Movement & No Animation
            anim.SetBool(WALK_ANIMATION, false);
        }
    }

    void PlayerJump()
    {
        if(Input.GetButtonDown("Jump") && isGrounded)
        {
            isGrounded = false;
            myBody.AddForce(new Vector2(0f, jumpForce), ForceMode2D.Impulse);
        }
    }

    private void OnCollisionEnter2D(Collision2D collision)
    {
        if(collision.gameObject.CompareTag(Ground_TAG))
            isGrounded = true;

        if(collision.gameObject.CompareTag(ENEMY_TAG))
            Destroy(gameObject);
    }

    private void OnTriggerEnter2D(Collider2D collision)
    {
        if (collision.CompareTag(ENEMY_TAG))
            Destroy(gameObject);
    }
}

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

public class CameraFollow : MonoBehaviour
{
    private Transform player;

    private Vector3 tempPos;

    [SerializeField]
    private float minX, maxX;

    void Start()
    {
        player = GameObject.FindWithTag("Player").transform;
    }

    void LateUpdate()
    {
        // Edit -> Project settings -> Time -> Fixed Timestep -> 0.02 (default)
        // LateUpdate run after the Update method run.
        // LateUpdate method is used to control the camera smooth movement by following the player.

        if (!player) return; // when player is destroy due to collision with enemy or something then this code runs.

        tempPos = transform.position;
        tempPos.x = player.position.x;

        if (tempPos.x < minX) tempPos.x = minX;
        if (tempPos.x > maxX) tempPos.x = maxX;

        transform.position = tempPos;
    }
}

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

public class Collector : MonoBehaviour
{
    private void OnTriggerEnter2D(Collider2D collision)
    {
        if(collision.CompareTag("Enemy") || collision.CompareTag("Player"))
            Destroy(collision.gameObject);
    }
}

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

public class Monster : MonoBehaviour
{
    [HideInInspector]
    public float speed;

    private Rigidbody2D myBody;

    void Awake()
    {
        myBody = GetComponent<Rigidbody2D>();
    }

    void FixedUpdate()
    {
        myBody.velocity = new Vector2(speed, myBody.velocity.y);
    }
}

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

public class GameManager : MonoBehaviour
{
    public static GameManager instance;

    [SerializeField]
    private GameObject[] characters;

    private int _charIndex;
    public int CharIndex
    {
        get { return _charIndex; }
        set { _charIndex = value; }
    }

    private void Awake()
    {
        if (instance == null) 
        {
            instance = this;
            DontDestroyOnLoad(gameObject); // to keep Game Manager obj on Gameplay scene
        } else
        {
            Destroy(gameObject); // destroy the duplicate obj if available there
        }
    }

    private void OnEnable()
    {
        SceneManager.sceneLoaded += OnLevelFinishedLoading;
    }

    private void OnDisable()
    {
        SceneManager.sceneLoaded -= OnLevelFinishedLoading;
    }

    // delegates & events
    void OnLevelFinishedLoading(Scene scene, LoadSceneMode mode)
    {
        if(scene.name == "Gameplay")
            Instantiate(characters[CharIndex]);
    }
}

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

public class GameplayUIController : MonoBehaviour
{
    public void RestartGame()
    {
        SceneManager.LoadScene(SceneManager.GetActiveScene().name); // Instead of SceneManager.LoadScene("Gameplay");
    }

    public void HomeButton()
    {
        SceneManager.LoadScene("MainMenu");
    }

}

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

public class MainMenuController : MonoBehaviour
{
    public void PlayGame()
    {
        int selectedCharacter = int.Parse(UnityEngine.EventSystems.EventSystem.current.currentSelectedGameObject.name);

        GameManager.instance.CharIndex = selectedCharacter;

        SceneManager.LoadScene("Gameplay"); // Navigating "Gameplay" scene
    }
}

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

public class MonsterSpawner : MonoBehaviour
{
    [SerializeField]
    private GameObject[] monsterReference;

    private GameObject spawnedMonster;

    [SerializeField]
    private Transform leftPos, rightPos;

    private int randomIndex, randomSide;

    void Start()
    {
        StartCoroutine(SpawnMonsters());
    }

    IEnumerator SpawnMonsters()
    {
        while(true)
        {
            yield return new WaitForSeconds(Random.Range(1, 5));

            randomIndex = Random.Range(0, monsterReference.Length);
            randomSide = Random.Range(0, 2);

            spawnedMonster = Instantiate(monsterReference[randomIndex]);

            if(randomSide == 0)
            {
                // left side
                spawnedMonster.transform.position = leftPos.position;
                spawnedMonster.GetComponent<Monster>().speed = Random.Range(4, 10);
            } else
            {
                // right side
                spawnedMonster.transform.position = rightPos.position;
                spawnedMonster.GetComponent<Monster>().speed = -Random.Range(4, 10);
                spawnedMonster.transform.localScale = new Vector3(-1f, 1f, 1f); // x-axis: -1f for fliping the monster
            }
        }
    }
}