How to make my topdown movement ignore facing and always move "up", "down", "left", "right" on the screen?

Scripting
1

Hello trying to make a topdown game with WASD for movement and the player turning to follow mouse. I have the lookatmouse script working but now my movement when my character looks to the right on screen pressing “a” to go left moves character left not screen left. How do I make it ignore the direction my character is facing?

public class LookAtMouse : MonoBehaviour
{
    private Camera cam;
    // Start is called before the first frame update
    void Start()
    {
        cam = Camera.main;
    }

    // Update is called once per frame
    void Update()
    {
        Vector3 mousePos = (Vector2)cam.ScreenToWorldPoint(Input.mousePosition);
        float angleRad = Mathf.Atan2(mousePos.y - transform.position.y, mousePos.x - transform.position.x);
        float angleDeg = (180 / Mathf.PI) * angleRad - 90;

        transform.rotation = Quaternion.Euler(0f, 0f, angleDeg);
    }
}

public class PlayerControllerAlternate : MonoBehaviour
{
    float playerSpeed = 1.0f;
    // Start is called before the first frame update
    void Start()
    {
        
    }

    // Update is called once per frame
    void Update()
    {
        if (Input.GetKey(KeyCode.W))
        {
            transform.Translate(Vector2.up * playerSpeed * Time.deltaTime);
        }
        if (Input.GetKey(KeyCode.S))
        {
            transform.Translate(Vector2.down * playerSpeed * Time.deltaTime);
        }
        if (Input.GetKey(KeyCode.A))
        {
            transform.Translate(Vector2.left * playerSpeed * Time.deltaTime);
        }
        if (Input.GetKey(KeyCode.D))
        {
            transform.Translate(Vector2.right * playerSpeed * Time.deltaTime);
        }

    }
}
2

Translate has a second parameter where you can specify whether the movement is in local space or world space.

transform.Translate(Vector2.up * playerSpeed * Time.deltaTime, Space.World);

BTW - you could move your transform using the keys with a single line:

void Update()
{
	transform.Translate(new Vector3(Input.GetAxis("Horizontal"),Input.GetAxis("Vertical"),0) * playerSpeed * Time.deltaTime, Space.World);
}

Although you don’t really want to be moving a character using transform.Translate because the physics engine will struggle to prevent it from walking through a wall. Instead we move 2D physics objects around using MovePosition or AddForce like this:

Rigidbody2D rb;

void Start()
{
	rb=GetComponent<Rigidbody2D>();
}

void FixedUpdate()
{
	rb.MovePosition(rb.position + new Vector2(Input.GetAxis("Horizontal"),Input.GetAxis("Vertical")) * playerSpeed * Time.deltaTime);
}