Character Controller - Simple Move

Player.cs

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Player : MonoBehaviour
{
    public float rotationSpeed = 4f;
    public float moveSpeed = 25f;

    private CharacterController characterController;
    private float yaw = 0f;

    // Start is called before the first frame update
    void Awake()
    {
        characterController = GetComponent<CharacterController>();
        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible = false;        
    }

    // Update is called once per frame
    void Update()
    {
        yaw += Input.GetAxis("Mouse X") * rotationSpeed;
        Vector3 moveDir = transform.forward * Input.GetAxis("Vertical") * moveSpeed;

        transform.eulerAngles = new Vector3(0f, yaw, 0f);
        moveDir += transform.right * Input.GetAxis("Horizontal") * moveSpeed;        

        characterController.SimpleMove(moveDir);
    }
}