【Unity】【NGUI】NGUIにVirtual Joystick(NGUI用)を追加してみた ref: http://qiita.com/shori0917/items/0b3237eb13889d3ea053

Player.cs

    UIJoystick joystick;

    void Start() {
        this.joystick = GameObject.FindGameObjectWithTag("Joystick").GetComponent<UIJoystick>();
    }

    void Update() {

        if (this.joystick.position.y > 0)
        {
            transform.position += new Vector3(0, _speed * Time.deltaTime, 0);
        }
        else if (this.joystick.position.y < 0)
        {
            transform.position -= new Vector3(0, _speed * Time.deltaTime, 0);
        }
        if (this.joystick.position.x > 0)
        {
            transform.position += new Vector3(_speed * Time.deltaTime, 0, 0);
        }
        else if (this.joystick.position.x < 0)
        {
            transform.position -= new Vector3(_speed * Time.deltaTime, 0, 0);
        }
    }