Added a bunch of features

Assets/Scripts/Flash.cs

@@ -0,0 +1,41 @@
+using System.Collections;
+using System.Collections.Generic;
+using UnityEngine;
+
+public class Flash : MonoBehaviour {
+	SpriteRenderer spriteRenderer;
+
+	float alpha = 1.0f;
+	const float gradient = 0.1f;
+	const float period = 0.1f;
+
+	float lastClick; //prevent double exposure
+
+	void Awake() {
+		spriteRenderer = GetComponent<SpriteRenderer> ();
+
+		spriteRenderer.color = new Color (1f, 1f, 1f, 0f);
+	}
+
+	public void StartFlash() {
+		StartCoroutine (FlashCoroutine ());
+	}
+
+	IEnumerator FlashCoroutine() {
+		lastClick = Time.time;
+		float thisClick = lastClick;
+
+		alpha = 1.0f;
+
+		while (alpha > 0) {
+			yield return new WaitForSeconds (period);
+
+			if (thisClick != lastClick) {
+				break;
+			}
+
+			alpha -= gradient;
+			spriteRenderer.color = new Color (1f, 1f, 1f, alpha);
+		}
+	}
+}