Character Controller

using UnityEngine;
using System.Collections;

public class CharacterController : MonoBehaviour
{

    public float mouseSpeedX;
    public float mouseSpeedY;
    public float playerMoveSpeed;
    public float jumpForce;

    float verticalLookRotation;
    Rigidbody rb;
    Ray ray;

    bool isGrouded() {
        Vector3 pos = transform.position; pos.y -= 0.98f;
        Collider[] cols = Physics.OverlapSphere(pos, 0.2f);
        if (cols.Length > 1) return true;
        else return false;
    }

    void Start() {
        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible = false;
        rb = GetComponent<Rigidbody>();
    }

    void Update() {

        if (Input.GetKeyDown(KeyCode.Escape)) {
            Cursor.lockState = CursorLockMode.None;
            Cursor.visible = true;
        }
        if (Input.GetMouseButtonDown(0)) {
            Cursor.lockState = CursorLockMode.Locked;
            Cursor.visible = false;
        }
        Camera.main.transform.localPosition = new Vector3(0f, 0.75f, 0f);
        transform.Rotate(Vector3.up * Input.GetAxis("Mouse X") * Time.deltaTime * mouseSpeedX);
        verticalLookRotation += Input.GetAxis("Mouse Y") * Time.deltaTime * mouseSpeedY;
        verticalLookRotation = Mathf.Clamp(verticalLookRotation, -90, 75);
        Camera.main.transform.localEulerAngles = Vector3.left * verticalLookRotation;

        rb.velocity = new Vector3(0f, rb.velocity.y, 0f);
        float finalMoveSpeed = (Input.GetKey(KeyCode.LeftShift)) ? playerMoveSpeed * 1.5f : playerMoveSpeed;

        Vector3 movement = transform.TransformDirection(new Vector3(Input.GetAxis("Horizontal"), 0f, Input.GetAxis("Vertical")).normalized);

        rb.MovePosition(transform.position + movement * finalMoveSpeed);

        if (Input.GetKey(KeyCode.Space) && isGrouded()) rb.velocity = new Vector3(rb.velocity.x, jumpForce, rb.velocity.z);
    }
}