1st version

Assets/Prefabs.meta

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Assets/Prefabs/BaseBullet.prefab.meta

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Assets/Prefabs/BaseEnemyBullet.prefab.meta

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Assets/Prefabs/Enemy1.prefab.meta

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Assets/Scenes.meta

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Assets/Scenes/BaseScene.unity.meta

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Assets/Scripts.meta

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Assets/Scripts/BaseEnemyManager.cs

+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class BaseEnemyManager : MonoBehaviour
+{
+    [SerializeField]
+    float minSpeed = 4;
+    [SerializeField]
+    float maxSpeed = 6;
+    [SerializeField]
+    float minTimeBetweenBullets = 0.4f;
+    [SerializeField]
+    float maxTimeBetweenBullets = 0.6f;
+
+    [SerializeField]
+    Vector3 moveDirection = new Vector3(-1, 0, 0);
+    [SerializeField]
+    Vector3 shootDirection = new Vector3(-1, 0, 0);
+
+    [SerializeField]
+    ShooterManager shooterManager;
+    [SerializeField]
+    MoveableManager moveableManager;
+    [SerializeField]
+    Renderer renderer;
+
+    // Use this for initialization
+    void Start ()
+    {
+        if (moveableManager)
+        {
+            moveableManager.speed = Random.Range(minSpeed, maxSpeed);
+        }
+        if (shooterManager)
+        {
+            shooterManager.timeBetweenBullets = Random.Range(minTimeBetweenBullets, maxTimeBetweenBullets);
+        }
+	}
+	
+	// Update is called once per frame
+	void Update ()
+    {
+        moveableManager.Move(moveDirection);
+        shooterManager.Shoot(shootDirection);
+        if (Time.time > 0.05f && renderer && !renderer.isVisible)
+        {
+            Destroy(this.gameObject);
+        }
+    }
+}

Assets/Scripts/BaseEnemyManager.cs.meta

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Assets/Scripts/BulletManager.cs

+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class BulletManager : MonoBehaviour
+{
+    [SerializeField]
+    private MoveableManager moveableManager;
+    [SerializeField]
+    private Renderer renderer;
+    [SerializeField]
+    private int damage = 1;
+
+    public Vector3 direction { private get; set; }
+    public bool player { private get; set; }
+
+    private void Update()
+    {
+        moveableManager.Move(direction);
+        if (!renderer.isVisible)
+        {
+            Destroy(this.gameObject);
+        }
+    }
+
+    private void OnTriggerEnter2D(Collider2D collision)
+    {
+        GameObject other = collision.gameObject;
+        if ((player && other.CompareTag("Enemy")) || (!player && other.CompareTag("Player")))
+        {
+            Destroy(this.gameObject);
+            HealthManager otherHealthManager = other.GetComponent<HealthManager>();
+            if(otherHealthManager)
+            {
+                otherHealthManager.TakeDamage(damage);
+            }
+        }
+    }
+}

Assets/Scripts/BulletManager.cs.meta

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Assets/Scripts/EnemyGenerator.cs

+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class EnemyGenerator : MonoBehaviour {
+
+    [SerializeField]
+    GameObject[] enemyPrefabs;
+    [SerializeField]
+    float minY = -8;
+    [SerializeField]
+    float maxY = 8;
+    [SerializeField]
+    float X = 10;
+    [SerializeField]
+    float timeBetweenEnemies = 0.5f;
+    float lastEnemyTime = float.NegativeInfinity;
+
+	// Use this for initialization
+	void Start () {
+		
+	}
+	
+	// Update is called once per frame
+	void Update ()
+    {
+        if (enemyPrefabs.Length > 0 && Time.time - lastEnemyTime > timeBetweenEnemies)
+        {
+            int selectedEnemy = Random.Range((int)0, (int)enemyPrefabs.Length - 1);
+            float Y = Random.Range(minY, maxY);
+            GameObject newEnemy = Instantiate(enemyPrefabs[selectedEnemy]);
+            newEnemy.transform.position = new Vector3(X, Y, 0);
+            lastEnemyTime = Time.time;
+        }
+	}
+}

Assets/Scripts/EnemyGenerator.cs.meta

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Assets/Scripts/EnergyManager.cs

+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class EnergyManager : MonoBehaviour {
+
+	// Use this for initialization
+	void Start () {
+		
+	}
+	
+	// Update is called once per frame
+	void Update () {
+		
+	}
+}

Assets/Scripts/EnergyManager.cs.meta

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Assets/Scripts/HealthManager.cs

+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class HealthManager : MonoBehaviour
+{
+    [SerializeField] int maxHealth = 1;
+    int currentHealth;
+
+    private void Start()
+    {
+        currentHealth = maxHealth;
+    }
+
+    public void TakeDamage(int damage)
+    {
+        currentHealth -= damage;
+        if(currentHealth <= 0)
+        {
+            Destroy(this.gameObject);
+        }
+    }
+}