2 cubes go through each other instead of stopping

There are several reasons for that two happen:

• you are moving the cubes using transform.position instead of Rigibody.AddForce

• your cubes have their layermasks set up so that they ignore collisions between them.

c#:

 float amtToMove = Input.GetAxis("Horizontal") * playerSpeed;
             transform.Translate(Vector3.right*amtToMove*Time.deltaTime    );
             float amtToMove2 = Input.GetAxis("Vertical") * playerSpeed;
             transform.Translate(Vector3.up*amtToMove2*Time.deltaTime    );

How can I make this "Rigidbody.AddForce"?

http://docs.unity3d.com/Documentation/ScriptReference/Rigidbody.AddForce.html

You would replace your transform.Translate with transform.rigidbody.AddForce.

Oh also. Please go back to your old questions and accept the right answers. I just had a quick look at your profile and saw you had only one closed questions and that one was closed by a moderator/high-karma user. If your question on UA is solved you should always accept the right answer so that the question gets marked as solved. This way no one will try to answer already answered questions.

Now the Cube won't move at all. Here is my script: c#:

   float amtToMove = Input.GetAxis("Horizontal") * playerSpeed;
              transform.rigidbody.AddForce(Vector3.right*amtToMove*Time.deltaTime    );
             float amtToMove2 = Input.GetAxis("Vertical") * playerSpeed;
              transform.rigidbody.AddForce(Vector3.up*amtToMove2*Time.deltaTime    );