Как мне в начале игры сделать меню в котором будет кнопка старт и выйти помогите пожалуйста. Вот мой код

import pygame

import random
import os

WIDTH = 1280  # ширина игрового окна 
HEIGHT = 720  # высота игрового окна
FPS = 60 # частота кадров в секунду


BLACK = (0, 0, 0)
WHITE = (255, 255, 255)
RED = (255, 0, 0)
GREEN = (0, 255, 0)
BLUE = (0, 0, 255) 
YELLOW = (255, 255, 0)

screen = pygame.display.set_mode((WIDTH, HEIGHT)) img_dir =
os.path.dirname(__file__) player_image =
pygame.image.load(os.path.join(img_dir,
                                              'CHECHEN.png')).convert() img_dir = os.path.dirname(__file__)
bullet_image = pygame.image.load(os.path.join(img_dir,
                                              'PATRON.png')).convert() img_dir = os.path.dirname(__file__)
enemy_image = pygame.image.load(os.path.join(img_dir,
                                              'DFDFD.png')).convert()





class Enemy(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((15, 15))
        self.image = pygame.transform.scale(enemy_image,
                                            (200, 200))

        self.rect = self.image.get_rect()
        self.rect.x = random.randrange(WIDTH - self.rect.width)
        self.rect.y = random.randrange(-100, -40)
        self.speedy = random.randrange(1, 2)
        self.speedx = random.randrange(-1, 2)

    def update(self):
        self.rect.x += self.speedx
        self.rect.y += self.speedy
        if self.rect.top > HEIGHT + 10 or self.rect.left < -100 \
                or self.rect.right > WIDTH + 20:
            self.rect.x = random.randrange(WIDTH - self.rect.width)
            self.rect.y = random.randrange(-50, -40)
            self.speedy = random.randrange(1, 2)


class Bullet(pygame.sprite.Sprite):
    def __init__(self, x, y, way):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((30, 40))
        self.image = pygame.transform.scale(bullet_image,
                                            (20, 20))
        self.rect = self.image.get_rect()
        self.rect.bottom = y
        self.rect.centerx = x
        if way == 1:
            self.speedy = -9
            self.speedx = 0
        elif way == 2:
            self.speedy = 0
            self.speedx = 9
        elif way == 3:
            self.speedy = 0
            self.speedx = -9
        elif way == 4:
            self.speedy = 9
            self.speedx = 0

    def update(self):
        self.rect.y += self.speedy
        self.rect.x += self.speedx
        if self.rect.bottom < 0:
            self.kill()



class Player(pygame.sprite.Sprite):
    def __init__(self):
        pygame.sprite.Sprite.__init__(self)
        self.image = pygame.Surface((40, 20))
        self.image = pygame.transform.scale(player_image,
                                            (100,100))

        self.rect = self.image.get_rect()
        self.image = player_image
        self.rect = self.image.get_rect()
        self.rect.centerx = WIDTH / 2
        self.rect.bottom = HEIGHT - 3
        self.speedx = 0
        self.speedy = 0
        self.way = 1

    def update(self):
        self.speedx = 0
        self.speedy = 0
        keystate = pygame.key.get_pressed()
        if keystate[pygame.K_LEFT]:
            self.way = 3
        elif keystate[pygame.K_RIGHT]:
            self.way = 2
        elif keystate[pygame.K_UP]:
            self.way = 1
        elif keystate[pygame.K_DOWN]:
            self.way = 4

        if keystate[pygame.K_a]:
            self.speedx = -5

        elif keystate[pygame.K_d]:
            self.speedx = 5

        elif keystate[pygame.K_w]:
            self.speedy = 5

        elif keystate[pygame.K_s]:
            self.speedy = -5

        self.rect.x += self.speedx
        self.rect.y -= self.speedy
        if self.rect.left < 0:
            self.rect.left = 0
        if self.rect.right > WIDTH:
            self.rect.right = WIDTH
        if self.rect.top < 0:
            self.rect.top = 0
        if self.rect.bottom > HEIGHT:
            self.rect.bottom = HEIGHT

    def shoot(self):
        bullet = Bullet(self.rect.centerx, self.rect.top, self.way)
        all_sprites.add(bullet)
        bullets.add(bullet)


# начало pygame.init() pygame.mixer.init()  # для звука pygame.display.set_caption("My Game") screen.fill(WHITE)
pygame.display.flip() clock = pygame.time.Clock()

all_sprites = pygame.sprite.Group() bullets = pygame.sprite.Group()
enemies = pygame.sprite.Group() player = Player()
all_sprites.add(player)

for i in range(10):
    enem = Enemy()
    all_sprites.add(enem)
    enemies.add(enem)

running = True while running:
    clock.tick(FPS)
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_SPACE:
                player.shoot()


    all_sprites.update()
    hits = pygame.sprite.groupcollide(enemies, bullets, True, True)
    for hit in hits:
        enem = Enemy()
        all_sprites.add(enem)
        enemies.add(enem)
    hits = pygame.sprite.spritecollide(player, enemies, False)
    if hits:
        running = False

    background = pygame.image.load("АЩТ ВДЫ.jpg")
    screen.blit(background, (0, 0))
    all_sprites.draw(screen)
    pygame.display.flip()

pygame.quit()