Common Enemies and their special abilities (2D Space Shooter)

Common Enemies spawn more frequently and share the basic attack of two laser shots at a time. Enemy A moves straight, can avoid one shot. Enemy B moves swinging left and right and has two special attacks. Enemy B may spawn carrying a homing projectile or a shield. If Enemy B survives his first round, it gains a new shield when reentering the map.

• Enemy Avoid Shot
• Smart Enemy (Shoots behind the player)
• Enemy Shields

First, let’s analyze how Enemy A can Avoid one Shot.

Enemy avoiding lasers by moving randomly left or right.

// This method is inside the enemy script 
public void AvoidShot()
    {
        int move = Random.Range(0, 2);
        float t = 1;
        Vector2 _currentPosition = transform.position;
        Vector2 _movedPositionLeft = new Vector2(transform.position.x - 2, transform.position.y);
        Vector2 _movedPositionRight = new Vector2(transform.position.x + 2, transform.position.y);

        if (move == 0)
        {
            transform.position = Vector2.Lerp(_currentPosition, _movedPositionLeft, t);
        }
        else
        {
            transform.position = Vector2.Lerp(_currentPosition, _movedPositionRight, t);
        }
    }

Then an invisible box collider is carried in front of every enemy to detect a laser.

//inside the Shot Sensor script
[SerializeField]
    private bool shotAvoided = false;
    private void OnTriggerEnter2D(Collider2D other)
    {
        if (other.tag == "Laser" && !shotAvoided)
        {
            transform.GetComponentInParent<Enemy>().AvoidShot();
            shotAvoided= true;
        }
    }

This way the sensor only works for one shot. If these enemies get close to each other, they become very tricky to shoot at.

Enemy B Smart shot is a homing projectile that burns power-ups and follow the player.

That laser triangle with the metal ball is the homing missile. When the enemy B enters the arena again, it gains a new shield! The homing projectiles can be shot at to avoid damage, but it requires skill and speed.

Enemy B starts with Special ability 1 and then gains a shield with specialID 0

//Enemy B Script
//inside the Start Mehtod, these are declared along the switch 
//that determines if the Enemy B has the homing beam or shield
void Start() 
  {

        _shootingOn = true;
        _specialAbilityID = Random.Range(0, 2);
        _shieldIsOn = false;

        switch (_specialAbilityID)
        {
            case 0:
                _offset = Random.Range(-2, 2);
                ShieldOn();
                break;
            case 1:
                _offset = Random.Range(-6, 6);
                _homingBeam.gameObject.SetActive(true);
                break;
        }
  }

// this code is called inside the movement when enemy leaves screen
if (transform.position.y < -6.5)
        {
            EnemyBSpecials();
            float randomX = Random.Range(-9f, 9f);
            transform.position = new Vector3(randomX, 8, 0);
        }
private void ShootHomingLaser()
  {
        //This method is called right after 
        //the homing projectile is unparented
        //and gets ID 0 to obtain shields
        _homingBeamScript.ActivateSeeking();
        _specialAbilityID = 0;
  }

//Shielding
void EnemyBSpecials()
    {
        switch (_specialAbilityID)
        {
            case 0:
                ShieldOn();
                break;
            case 1:
                if (_homingBeam != null)
                {
                    _homingBeam.transform.SetParent(null);
                    Debug.Log("Homing unparented");
                }
                ShootHomingLaser();
                break;
        }
    }

 private void ShieldOn()
    {
        _enemShieldRenderer.color = Color.red;
        _enemyShield.gameObject.SetActive(true);
        _shieldIsOn = true;
    }
//With this Set up, inside the OnTriggerEnter2D() 
else if (_shieldIsOn && other.tag == "Laser")
        {
            {
                other.gameObject.SetActive(false);
                _enemyShield.gameObject.SetActive(false);
                _shieldIsOn = false;
            }
        }
else if (other.tag == "Laser" && !_shieldIsOn)
        {
            other.gameObject.SetActive(false);
            if (_spawnManagerScript != null)
            {
                OnEnemyDeath();
            }
        }

If Enemy B starts with an ID 0, it never carries the homing beam. Making it less frequent for homing beams to appear. I’ll explain the homing beam script functionality on a separate article where I’ll also describe a homing projectile used by the player.