SideScrolling Mouse Pointer Aim - Help

Hello everyone. i would like to make a SideScrolling shooting game. something like this.

http://www.youtube.com/watch?v=r84uyPRzNaQ

im using this coding for following the mouse, but instead of following, it makes circles. what does it go wrong? could anyone help me?

using UnityEngine; using System.Collections;

[AddComponentMenu("Camera-Control/Mouse Look")]

public class MouseLook : MonoBehaviour {

public enum RotationAxes { MouseXAndY = 0, MouseX = 1, MouseY = 2 }

public RotationAxes axes = RotationAxes.MouseXAndY;

public float sensitivityX = 15F; public float sensitivityY = 0F;

public float minimumX = 0F; public float maximumX = 0F;

public float minimumY = -60F; public float maximumY = 60F;

float rotationY = 0F;

void Update () {

if (axes == RotationAxes.MouseXAndY) {

float rotationX = transform.localEulerAngles.y - Input.GetAxis("Mouse X") * sensitivityX;

rotationY += Input.GetAxis("Mouse Y") * sensitivityY;

rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);

transform.localEulerAngles = new Vector3(-rotationY, rotationX, 0);

}

else if (axes == RotationAxes.MouseX)

{

transform.Rotate(0, Input.GetAxis("Mouse X") * sensitivityX, 0);

}

else {

rotationY += Input.GetAxis("Mouse Y") * sensitivityY;

rotationY = Mathf.Clamp (rotationY, minimumY, maximumY);

transform.localEulerAngles = new Vector3(-rotationY, transform.localEulerAngles.y, 0);

}

} void Start () { if (rigidbody) rigidbody.freezeRotation = true;

}

}