Restarting a snake game after game over screen appears in pygame

Question

in the game that I have found on github there is a game over screen that shows your score, now I want to make the game restart if you press space so that you don't need to close the program and open it again to play it again. The problem isn't how to make the game restart when you press space but to actually make it restart. Here is the code:

import pygame
import random
import sys
import time

# Difficulty settings
# Easy      ->  10
# Medium    ->  25
# Hard      ->  40
# Harder    ->  60
# Impossible->  120
difficulty = 25

# Window size
frame_size_x = 720
frame_size_y = 480

# Checks for errors encountered
check_errors = pygame.init()
# pygame.init() example output -> (6, 0)
# second number in tuple gives number of errors
if check_errors[1] > 0:
    print(f'[!] Had {check_errors[1]} errors when initialising game, exiting...')
    sys.exit(-1)
else:
    print('[+] Game successfully initialised')

# Initialise game window
pygame.display.set_caption('Snake Eater')
game_window = pygame.display.set_mode((frame_size_x, frame_size_y))

# Colors (R, G, B)
black = pygame.Color(0, 0, 0)
white = pygame.Color(255, 255, 255)
red = pygame.Color(255, 0, 0)
green = pygame.Color(0, 255, 0)
blue = pygame.Color(0, 0, 255)

# FPS (frames per second) controller
fps_controller = pygame.time.Clock()

# Game variables
snake_pos = [100, 50]
snake_body = [[100, 50], [100 - 10, 50], [100 - (2 * 10), 50]]

food_pos = [random.randrange(1, (frame_size_x // 10)) * 10, random.randrange(1, (frame_size_y // 10)) * 10]
food_spawn = True

direction = 'RIGHT'
change_to = direction

score = 0


# Game Over
def game_over():
    my_font = pygame.font.SysFont('times new roman', 90)
    game_over_surface = my_font.render('YOU DIED', True, red)
    game_over_rect = game_over_surface.get_rect()
    game_over_rect.midtop = (frame_size_x / 2, frame_size_y / 4)
    game_window.fill(black)
    game_window.blit(game_over_surface, game_over_rect)
    show_score(0, red, 'times', 20)
    pygame.display.update()
    time.sleep(3)
    pygame.quit()
    sys.exit()


# Score
def show_score(choice, color, font, size):
    score_font = pygame.font.SysFont(font, size)
    score_surface = score_font.render('Score : ' + str(score), True, color)
    score_rect = score_surface.get_rect()
    if choice == 1:
        score_rect.midtop = (frame_size_x - 100, 15)
    else:
        score_rect.midtop = (frame_size_x / 2, frame_size_y / 1.25)
    game_window.blit(score_surface, score_rect)
    # pygame.display.flip()


# Main logic
while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        # Whenever a key is pressed down
        elif event.type == pygame.KEYDOWN:
            # W -> Up; S -> Down; A -> Left; D -> Right
            if event.key == pygame.K_UP or event.key == ord('w'):
                change_to = 'UP'
            if event.key == pygame.K_DOWN or event.key == ord('s'):
                change_to = 'DOWN'
            if event.key == pygame.K_LEFT or event.key == ord('a'):
                change_to = 'LEFT'
            if event.key == pygame.K_RIGHT or event.key == ord('d'):
                change_to = 'RIGHT'
            # Esc -> Create event to quit the game
            if event.key == pygame.K_ESCAPE:
                pygame.event.post(pygame.event.Event(pygame.QUIT))

    # Making sure the snake cannot move in the opposite direction instantaneously
    if change_to == 'UP' and direction != 'DOWN':
        direction = 'UP'
    if change_to == 'DOWN' and direction != 'UP':
        direction = 'DOWN'
    if change_to == 'LEFT' and direction != 'RIGHT':
        direction = 'LEFT'
    if change_to == 'RIGHT' and direction != 'LEFT':
        direction = 'RIGHT'

    # Moving the snake
    if direction == 'UP':
        snake_pos[1] -= 10
    if direction == 'DOWN':
        snake_pos[1] += 10
    if direction == 'LEFT':
        snake_pos[0] -= 10
    if direction == 'RIGHT':
        snake_pos[0] += 10

    # Snake body growing mechanism
    snake_body.insert(0, list(snake_pos))
    if snake_pos[0] == food_pos[0] and snake_pos[1] == food_pos[1]:
        score += 1
        food_spawn = False
    else:
        snake_body.pop()

    # Spawning food on the screen
    if not food_spawn:
        food_pos = [random.randrange(1, (frame_size_x // 10)) * 10, random.randrange(1, (frame_size_y // 10)) * 10]
    food_spawn = True

    # GFX
    game_window.fill(black)
    for pos in snake_body:
        # Snake body
        # .draw.rect(play_surface, color, xy-coordinate)
        # xy-coordinate -> .Rect(x, y, size_x, size_y)
        pygame.draw.rect(game_window, green, pygame.Rect(pos[0], pos[1], 10, 10))

    # Snake food
    pygame.draw.rect(game_window, white, pygame.Rect(food_pos[0], food_pos[1], 10, 10))

    # Game Over conditions
    # Getting out of bounds
    if snake_pos[0] < 0 or snake_pos[0] > frame_size_x - 10:
        game_over()
    if snake_pos[1] < 0 or snake_pos[1] > frame_size_y - 10:
        game_over()
    # Touching the snake body
    for block in snake_body[1:]:
        if snake_pos[0] == block[0] and snake_pos[1] == block[1]:
            game_over()

    show_score(1, white, 'consolas', 20)
    # Refresh game screen
    pygame.display.update()
    # Refresh rate
    fps_controller.tick(difficulty)

Answer 1

Implement a function that initializes all the global game states:

def init_game():
    global snake_pos, snake_body
    global food_pos, food_spawn
    global direction, change_to, score
    
    # Game variables
    snake_pos = [100, 50]
    snake_body = [[100, 50], [100 - 10, 50], [100 - (2 * 10), 50]]

    food_pos = [random.randrange(1, (frame_size_x // 10)) * 10, random.randrange(1, (frame_size_y // 10)) * 10]
    food_spawn = True

    direction = 'RIGHT'
    change_to = direction

    score = 0

Invoke the function when SPACE is pressed:

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            pygame.quit()
            sys.exit()
        # Whenever a key is pressed down
        elif event.type == pygame.KEYDOWN:
            # [...]

            if event.key == pygame.K_SPACE:
                init_game()