Open-sourced some code

Scripts/Game Objects/Spawners/TimedSpawner.cs

@@ -0,0 +1,27 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class TimedSpawner : MonoBehaviour {
+	//inspector access elements
+	public GameObject prefab;
+	public float spawnDelay = 10f;
+	public int maxSpawns = 3;
+
+	//private members
+	float lastSpawnTime = float.NegativeInfinity;
+	List<GameObject> spawnList = new List<GameObject>();
+
+	//TODO: maybe all spawners should shut off (and monsters become inactive) when the player is too far away.
+	void Update() {
+		//prune the list
+		spawnList.RemoveAll(spawn => spawn == null);
+
+		//spawn if enough time has passed
+		if (Time.time - lastSpawnTime > spawnDelay && spawnList.Count < maxSpawns) {
+			lastSpawnTime = Time.time;
+
+			spawnList.Add(Instantiate(prefab, transform.position, Quaternion.identity, transform));
+		}
+	}
+}