Added Tetris functionality

Assets/Scripts/Spawner.cs

@@ -0,0 +1,25 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+using UnityEngine.UI;
+
+public class Spawner : MonoBehaviour
+{
+    // Array of groups
+    public GameObject[] groups;
+
+    // Constructor (called when game starts)
+    void Start()
+    {
+        // Spawn initial group
+        spawnNext();
+    }
+
+    public void spawnNext()
+    {
+        // Generates random index
+        int i = Random.Range(0, groups.Length);
+        // Spawn group at current spawner position
+        Instantiate(groups[i], transform.position, Quaternion.identity);
+    }
+}