Added enemies initial prefabs

Assets/__Scripts/BoundsCheck.cs

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+/// <summary>
+/// Keeps a GameObject on screen.
+/// Note that this ONLY works for an orthographic Main Camera at [ 0, 0, 0 ].
+/// </summary>
+
+public class BoundsCheck : MonoBehaviour
+{
+    [Header("Set in Inspector")]
+    public float radius = 1f;
+
+    [Header("Set Dynamically")]
+    public float camWidth;
+    public float camHeight;
+
+    void Awake() {
+        camHeight = Camera.main.orthographicSize;
+        camWidth = camHeight * Camera.main.aspect;
+     }
+
+    void LateUpdate () {
+        Vector3 pos = transform.position;
+
+        if (pos.x > camWidth - radius) {
+            pos.x = camWidth - radius;
+        }
+
+        if (pos.x < -camWidth + radius) {
+            pos.x = -camWidth + radius;
+        }
+
+        if (pos.y > camHeight - radius) {
+            pos.y = camHeight - radius;
+        }
+        if (pos.y < -camHeight + radius) {
+            pos.y = -camHeight + radius;
+        }
+
+        transform.position = pos;
+    }
+
+    // Draw the bounds in the Scene pane using OnDrawGizmos()
+    void OnDrawGizmos () {
+        if (!Application.isPlaying) return;
+        Vector3 boundSize = new Vector3(camWidth* 2, camHeight* 2, 0.1f);
+        Gizmos.DrawWireCube(Vector3.zero, boundSize);
+    }
+
+    // Start is called before the first frame update
+    void Start()
+    {
+        
+    }
+
+    // Update is called once per frame
+    void Update()
+    {
+        
+    }
+}

Assets/__Scripts/BoundsCheck.cs.meta

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Assets/__Scripts/Hero.cs

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class Hero : MonoBehaviour
+{
+    static public Hero S; 
+
+    [Header("Set in Inspector")]
+    // These fields control the movement of the ship
+    public float speed = 30;
+    public float rollMult = -45;
+    public float pitchMult = 30;
+
+    [Header("Set Dynamically")]
+    public float shieldLevel = 1;
+
+    void Awake() {
+        if (S == null) {
+            S = this; 
+        } else {
+            Debug.LogError("Hero.Awake() - Attempted to assign second Hero.S!");
+        }
+    }
+
+    // Start is called before the first frame update
+    void Start()
+    {
+        
+    }
+
+    // Update is called once per frame
+    void Update()
+    {
+        // Pull in information from the Input class
+        float xAxis = Input.GetAxis("Horizontal");
+        float yAxis = Input.GetAxis("Vertical");
+
+        // Change transform.position based on the axes
+        Vector3 pos = transform.position;
+        pos.x += xAxis * speed * Time.deltaTime;
+        pos.y += yAxis * speed * Time.deltaTime;
+        transform.position = pos;
+
+        // Rotate the ship to make it feel more dynamic 
+        transform.rotation = Quaternion.Euler(yAxis*pitchMult,xAxis*rollMult,0);
+    }
+}

Assets/__Scripts/Hero.cs.meta

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Assets/__Scripts/Shield.cs

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+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class Shield : MonoBehaviour
+{
+    [Header("Set in Inspector")]
+    public float rotationsPerSecond = 0.1f;
+
+    [Header("Set Dynamically")]
+    public int levelShown = 0;
+
+    // This non-public variable will not appear in the Inspector
+    Material mat;
+    // Start is called before the first frame update
+    void Start()
+    {
+        mat = GetComponent<Renderer>().material;
+    }
+
+    // Update is called once per frame
+    void Update()
+    {
+        // Read the current shield level from the Hero Singleton
+        int currLevel = Mathf.FloorToInt(Hero.S.shieldLevel);
+        // If this is different from levelShown...
+        if (levelShown != currLevel) {
+            levelShown = currLevel;
+            // Adjust the texture offset to show different shield level
+            mat.mainTextureOffset = new Vector2( 0.2f*levelShown, 0);
+        }
+        // Rotate the shield a bit every frame in a time-based way
+        float rZ = -(rotationsPerSecond*Time.time*3600) % 360f;
+        transform.rotation = Quaternion.Euler( 0, 0, rZ );
+    }
+}

Assets/__Scripts/Shield.cs.meta

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