Zombie AI Help

Here is a helpful YouTube tutorial.

You don't provide a script, so I have to guess at how you have thing setup. I'm assuming you are using a sprite for your zombie. I'm also assuming that your zombie faces right when its rotation is (0,0,0). With a sprite, it is better to flip it on the 'x' by rotating around the 'y' axis. Change the local scale (a common approach I see in question to UA), can result in problems with the collider. Merge this logic into your code:

 #pragma strict
 
 var player : transform;
    
 function Start() 
     player = GameObject.Find("Player").transform;
 }
 
 function Update() {
 
     if (player.position.x < transform.position.x) {
         transform.eulerAngles = Vector3(0,180,0);
     }
     else {
         transform.rotation = Quaternion.identity;
     }
 }