OTG_2/Assets/_Scripts/SimpleFPSController.cs

using UnityEngine;

[RequireComponent(typeof(CharacterController))]
public class SimpleFPSController : MonoBehaviour
{
    public Camera playerCamera;
    public float moveSpeed = 6f;
    public float mouseSensitivity = 2f;
    public float gravity = -20f;
    public float jumpHeight = 1.2f;
    public float recoilReturnSpeed = 18f;

    private CharacterController characterController;
    private float verticalVelocity;
    private float pitch;
    private float recoilPitchOffset;

    private void Awake()
    {
        characterController = GetComponent<CharacterController>();

        if (playerCamera == null)
            playerCamera = GetComponentInChildren<Camera>();
    }

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

    private void Update()
    {
        Look();
        Move();
    }

    public void AddRecoil(float amount)
    {
        recoilPitchOffset -= Mathf.Clamp(amount, 0f, 8f);
    }

    private void Look()
    {
        float mouseX = Input.GetAxis("Mouse X") * mouseSensitivity;
        float mouseY = Input.GetAxis("Mouse Y") * mouseSensitivity;

        transform.Rotate(Vector3.up * mouseX);
        pitch = Mathf.Clamp(pitch - mouseY, -85f, 85f);
        recoilPitchOffset = Mathf.MoveTowards(recoilPitchOffset, 0f, recoilReturnSpeed * Time.deltaTime);

        if (playerCamera != null)
            playerCamera.transform.localRotation = Quaternion.Euler(pitch + recoilPitchOffset, 0f, 0f);
    }

    private void Move()
    {
        Vector3 input = new Vector3(Input.GetAxisRaw("Horizontal"), 0f, Input.GetAxisRaw("Vertical"));
        input = Vector3.ClampMagnitude(input, 1f);

        Vector3 move = transform.TransformDirection(input) * moveSpeed;

        if (characterController.isGrounded && verticalVelocity < 0f)
            verticalVelocity = -2f;

        if (characterController.isGrounded && Input.GetKeyDown(KeyCode.Space))
            verticalVelocity = Mathf.Sqrt(jumpHeight * -2f * gravity);

        verticalVelocity += gravity * Time.deltaTime;
        move.y = verticalVelocity;

        characterController.Move(move * Time.deltaTime);
    }
}