实现经典贪吃蛇游戏可以使用 Python 的 pygame 库来进行。下面是一个简单的贪吃蛇游戏的实现示例：

import pygame  
import time  
import random  
pygame.init()  
# 定义一些常量  
WHITE = (255, 255, 255)  
YELLOW = (255, 255, 102)  
BLACK = (0, 0, 0)  
RED = (213, 50, 80)  
GREEN = (0, 255, 0)  
BLUE = (50, 153, 213)  
DISPLAY_WIDTH = 800  
DISPLAY_HEIGHT = 600  
SNAKE_BLOCK = 10  
SNAKE_SPEED = 15  
# 初始化显示窗口  
display = pygame.display.set_mode((DISPLAY_WIDTH, DISPLAY_HEIGHT))  
pygame.display.set_caption('贪吃蛇')  
clock = pygame.time.Clock()  
snake_font = pygame.font.SysFont(None, 50)  
def display_score(score):  
    value = snake_font.render("Your Score: " + str(score), True, BLACK)  
    display.blit(value, [0, 0])  
def draw_snake(snake_block, snake_list):  
    for block in snake_list:  
        pygame.draw.rect(display, BLACK, [block[0], block[1], snake_block, snake_block])  
def game_loop():  
    game_over = False  
    game_close = False  
    x = DISPLAY_WIDTH / 2  
    y = DISPLAY_HEIGHT / 2  
    x_change = 0  
    y_change = 0  
    snake_list = []  
    length_of_snake = 1  
    food_x = round(random.randrange(0, DISPLAY_WIDTH - SNAKE_BLOCK) / 10.0) * 10.0  
    food_y = round(random.randrange(0, DISPLAY_HEIGHT - SNAKE_BLOCK) / 10.0) * 10.0  
    while not game_over:  
        while game_close:  
            display.fill(BLUE)  
            display_score(length_of_snake - 1)  
            pygame.display.update()  
            for event in pygame.event.get():  
                if event.type == pygame.KEYDOWN:  
                    if event.key == pygame.K_q:  
                        game_over = True  
                        game_close = False  
                    if event.key == pygame.K_c:  
                        game_loop()  
        for event in pygame.event.get():  
            if event.type == pygame.QUIT:  
                game_over = True  
            if event.type == pygame.KEYDOWN:  
                if event.key == pygame.K_LEFT:  
                    x_change = -SNAKE_BLOCK  
                    y_change = 0  
                elif event.key == pygame.K_RIGHT:  
                    x_change = SNAKE_BLOCK  
                    y_change = 0  
                elif event.key == pygame.K_UP:  
                    y_change = -SNAKE_BLOCK  
                    x_change = 0  
                elif event.key == pygame.K_DOWN:  
                    y_change = SNAKE_BLOCK  
                    x_change = 0  
        if x >= DISPLAY_WIDTH or x < 0 or y >= DISPLAY_HEIGHT or y < 0:  
            game_close = True  
        x += x_change  
        y += y_change  
        display.fill(BLUE)  
        pygame.draw.rect(display, GREEN, [food_x, food_y, SNAKE_BLOCK, SNAKE_BLOCK])  
        snake_head = []  
        snake_head.append(x)  
        snake_head.append(y)  
        snake_list.append(snake_head)  
        if len(snake_list) > length_of_snake:  
            del snake_list[0]  
        for block in snake_list[:-1]:  
            if block == snake_head:  
                game_close = True  
        draw_snake(SNAKE_BLOCK, snake_list)  
        display_score(length_of_snake - 1)  
        pygame.display.update()  
        if x == food_x and y == food_y:  
            food_x = round(random.randrange(0, DISPLAY_WIDTH - SNAKE_BLOCK) / 10.0) * 10.0  
            food_y = round(random.randrange(0, DISPLAY_HEIGHT - SNAKE_BLOCK) / 10.0) * 10.0  
            length_of_snake += 1  
        clock.tick(SNAKE_SPEED)  
    pygame.quit()  
    quit()  
game_loop()  

运行游戏步骤：

1. 确保安装了 pygame 库，可以通过 pip install pygame 安装。
2. 复制上述代码到一个 Python 文件中，比如 snake_game.py。
3. 运行脚本：python snake_game.py。
4. 使用方向键（上下左右）来控制蛇的移动。
5. 按 Q 结束游戏，按 C 重启游戏。

此实现可以用作理解 pygame 的基础，随后可以在此基础上加上更多的功能和改进，比如不同难度级别、音效、不同的画面等。