public float speed = 3.0f;

// Update is called once per frame

void Update () {

if (Input.GetKey ("up")) {

transform.position += transform.forward * speed * Time.deltaTime;

}

if (Input.GetKey ("down")) {

transform.position -= transform.forward * speed * Time.deltaTime;

}

if (Input.GetKey("right")) {

transform.position += transform.right * speed * Time.deltaTime;

}

if (Input.GetKey ("left")) {

transform.position -= transform.right * speed * Time.deltaTime;

}