PlayerController

using UnityEngine;

public class PlayerController : MonoBehaviour {

    public float speed;
    public float jumpHeight;
    public float gravity = 20f;

    [Space]

    public Transform cameraTransform;
    public float horizontalSensitivity = 1f;
    public float verticalSensitivity = 1f;
    public float pitchMin = -70f;
    public float pitchMax = 80f;

    private CharacterController _controller;
    private Vector3 _input;
    private Vector3 _verticalVelocity;
    private Vector3 _yawVector;
    private Vector3 _currentPitch;

    private void Start() {
        Cursor.lockState = CursorLockMode.Locked;
        Cursor.visible = false;

        _controller = GetComponent<CharacterController>();
        _currentPitch = cameraTransform.localEulerAngles;
    }

    private void Update() {
        MoveUpdate();
        LookUpdate();
    }

    private void MoveUpdate() {
        bool isGrounded = _controller.isGrounded;

        _input.x = Input.GetAxis("Horizontal");
        _input.z = Input.GetAxis("Vertical");
        _input.Normalize();

        if (_verticalVelocity.y < -2f && isGrounded)
            _verticalVelocity.y = -1f;

        Vector3 moveVector = transform.forward * _input.z + transform.right * _input.x;
        _controller.Move(speed * Time.deltaTime * moveVector);

        if (Input.GetKeyDown(KeyCode.Space) && isGrounded) {
            _verticalVelocity.y = Mathf.Sqrt(jumpHeight * 2f * gravity);
        }

        _verticalVelocity.y -= gravity * Time.deltaTime;
        _controller.Move(_verticalVelocity * Time.deltaTime);
    }

    private void LookUpdate() {
        _yawVector.y = Input.GetAxis("Mouse X") * horizontalSensitivity;
        float pitch = Input.GetAxis("Mouse Y") * verticalSensitivity;

        transform.Rotate(_yawVector);

        _currentPitch.x = Mathf.Clamp(_currentPitch.x - pitch, pitchMin, pitchMax);
        cameraTransform.localEulerAngles = _currentPitch;
    }
}