CharMove.Update C# (CSharp) Method

    void Update()
    {
        Vector3 mousePosition = Camera.main.ScreenToWorldPoint(Input.mousePosition);
        Quaternion rotation = Quaternion.LookRotation(transform.position - mousePosition, Vector3.forward);
        transform.eulerAngles = new Vector3(0,0, rotation.eulerAngles.z);

        if (Input.GetKeyDown (KeyCode.LeftShift))
            maxSpeed = maxSpeed * 2;
        else if (Input.GetKeyUp (KeyCode.LeftShift))
            maxSpeed = maxSpeed / 2;

        if (Input.GetKey (KeyCode.D)) {
            speed += 1;
            if (speed > maxSpeed)
                speed = maxSpeed;
        } else if (Input.GetKey (KeyCode.A)) {
            speed -= 1;
            if (speed < -maxSpeed)
                speed = -maxSpeed;
        } else {
            if (speed > 0)
                speed -= 1;
            else if (speed < 0)
                speed += 1;
        }

        if (Input.GetKey (KeyCode.W)) {
            speedV += 1;
            if (speedV > maxSpeed)
                speedV = maxSpeed;
        } else if (Input.GetKey (KeyCode.S)) {
            speedV -= 1;
            if (speedV < -maxSpeed)
                speedV = -maxSpeed;
        } else {
            if (speedV > 0)
                speedV -= 1;
            else if (speedV < 0)
                speedV += 1;
        }
        transform.Translate (Vector3.right * speed * Time.deltaTime, Space.World);
        transform.Translate (Vector3.up * speedV * Time.deltaTime, Space.World);
    }