編寫一個小游戲可以使用Python的Pygame模塊來實現。以下是一個簡單的示例代碼來創建一個小游戲：

import pygame
import sys
import random

# 初始化pygame
pygame.init()

# 設置游戲窗口大小
WIDTH, HEIGHT = 800, 600
win = pygame.display.set_mode((WIDTH, HEIGHT))
pygame.display.set_caption("小游戲")

# 設置顏色
WHITE = (255, 255, 255)
RED = (255, 0, 0)

# 設置游戲變量
player_size = 50
player_pos = [WIDTH//2, HEIGHT-2*player_size]
enemy_size = 50
enemy_pos = [random.randint(0, WIDTH-enemy_size), 0]
enemy_list = [enemy_pos]
SPEED = 10

# 設置游戲循環
game_over = False
clock = pygame.time.Clock()

while not game_over:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

    # 游戲邏輯
    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT] and player_pos[0] > 0:
        player_pos[0] -= SPEED
    if keys[pygame.K_RIGHT] and player_pos[0] < WIDTH-player_size:
        player_pos[0] += SPEED

    # 移動敵人
    for idx, enemy in enumerate(enemy_list):
        if enemy[1] >= 0 and enemy[1] < HEIGHT:
            enemy[1] += SPEED
        else:
            enemy_list.pop(idx)

    if random.random() < 0.02:
        enemy_list.append([random.randint(0, WIDTH-enemy_size), 0])

    # 碰撞檢測
    for enemy in enemy_list:
        if enemy_pos[1] >= player_pos[1] and enemy_pos[1] <= player_pos[1]+player_size:
            if enemy_pos[0] >= player_pos[0] and enemy_pos[0] <= player_pos[0]+player_size:
                game_over = True

    # 渲染游戲場景
    win.fill(WHITE)

    # 渲染玩家
    pygame.draw.rect(win, RED, (player_pos[0], player_pos[1], player_size, player_size))

    # 渲染敵人
    for enemy in enemy_list:
        pygame.draw.rect(win, RED, (enemy[0], enemy[1], enemy_size, enemy_size))

    pygame.display.update()
    clock.tick(30)

這是一個簡單的游戲，玩家控制一個方塊躲避從上方下落的敵人方塊。玩家可以使用左右方向鍵移動自己的方塊，如果敵人方塊碰到玩家方塊則游戲結束。您可以根據自己的需求對游戲進行更多的定制和擴展。