Instantiate - overlapping / check collision when instantiated

The game should spawn static "enemies" randomly in a limited area, but the instantiated objects overlap each other quite often. My idea was to fix that by detecting collision and then just giving them a new random location not so far from the origin. Unfortunately, it doesn't work and i can't find out why.

Notes:

- "Enemy_Tx" is the tag used for three different types of enemies.
- Every object in scene should stay at 0 on y position, so on the grid.
- The link to an earlier version of the prototype in development: http://brenooshiro.itch.io/4th - Check it out and give me some feedback!

Thanks!

Here's the script​

Code (CSharp):

1.     void OnCollisionEnter (Collision collision)
2.     {
3.         if(collision.gameObject.tag == "Enemy_T1" || collision.gameObject.tag == "Enemy_T2" || collision.gameObject.tag == "Enemy_T3")
4.         {
5.             collision.gameObject.transform.position = new Vector3(transform.position.x + Random.Range(-10f, 10f), 0f, transform.position.z + Random.Range(-10f, 10f));
6.             print("collision worked");
7.         }
8.     }

 

instantiate and destroy don't cause OnCollisionEnter/Exit calls to occur. Try checking using an http://docs.unity3d.com/ScriptReference/Physics.OverlapSphere.html

 

Actually i had a problem. How do i check for collisions using OverlapSphere?