以下是一个简单的用Python编写的飞机大战游戏的源代码：

import pygame
import random

# 初始化游戏
pygame.init()

# 设置游戏窗口的尺寸
screen_width = 480
screen_height = 640
screen = pygame.display.set_mode((screen_width, screen_height))

# 设置游戏标题
pygame.display.set_caption("飞机大战")

# 加载背景图片
background = pygame.image.load("background.png")

# 加载玩家飞机图片
player_image = pygame.image.load("player.png")
player_rect = player_image.get_rect()
player_rect.topleft = ((screen_width - player_rect.width) // 2, screen_height - player_rect.height - 20)

# 加载敌机图片
enemy_image = pygame.image.load("enemy.png")

# 音效
bullet_sound = pygame.mixer.Sound("bullet.wav")
explosion_sound = pygame.mixer.Sound("explosion.wav")
pygame.mixer.music.load("background_music.mp3")
pygame.mixer.music.play(-1)

# 设置游戏帧率
clock = pygame.time.Clock()

# 玩家子弹列表
player_bullets = []

# 敌机列表
enemies = []
enemy_frequency = 0

# 设置游戏分数
score = 0
font = pygame.font.SysFont(None, 36)

# 游戏结束标志
game_over = False

# 游戏主循环
while not game_over:
    # 处理游戏事件
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            game_over = True

        if event.type == pygame.KEYDOWN:
            if event.key == pygame.K_SPACE:
                bullet_sound.play()
                player_bullet = pygame.Rect(player_rect.left + player_rect.width // 2 - 2, player_rect.top - 10, 4, 10)
                player_bullets.append(player_bullet)

    # 移动玩家飞机
    keys = pygame.key.get_pressed()
    if keys[pygame.K_LEFT] and player_rect.left > 0:
        player_rect.left -= 5
    if keys[pygame.K_RIGHT] and player_rect.right < screen_width:
        player_rect.left += 5
    if keys[pygame.K_UP] and player_rect.top > 0:
        player_rect.top -= 5
    if keys[pygame.K_DOWN] and player_rect.bottom < screen_height:
        player_rect.top += 5

    # 绘制游戏界面
    screen.blit(background, (0, 0))
    screen.blit(player_image, player_rect)

    # 绘制玩家子弹
    for bullet in player_bullets:
        bullet.top -= 10
        if bullet.top < -10:
            player_bullets.remove(bullet)
        pygame.draw.rect(screen, (255, 0, 0), bullet)

    # 生成敌机
    if enemy_frequency % 50 == 0:
        enemy_rect = enemy_image.get_rect()
        enemy_rect.topleft = (random.randint(0, screen_width - enemy_rect.width), -enemy_rect.height)
        enemies.append(enemy_rect)
    enemy_frequency += 1

    # 移动敌机
    for enemy in enemies:
        enemy.top += 5
        if enemy.top > screen_height:
            enemies.remove(enemy)

    # 检测子弹和敌机碰撞
    for bullet in player_bullets:
        for enemy in enemies:
            if bullet.colliderect(enemy):
                explosion_sound.play()
                enemies.remove(enemy)
                player_bullets.remove(bullet)
                score += 10

    # 绘制敌机
    for enemy in enemies:
        screen.blit(enemy_image, enemy)

    # 显示分数
    score_text = font.render("Score: " + str(score), True, (255, 255, 0))
    screen.blit(score_text, (10, 10))

    # 检测玩家飞机和敌机碰撞
    for enemy in enemies:
        if player_rect.colliderect(enemy):
            game_over = True

    # 更新游戏界面
    pygame.display.update()

    # 控制游戏帧率
    clock.tick(60)

# 游戏结束，显示最终得分
game_over_text = font.render("Game Over! Your Score: " + str(score), True, (255, 0, 0))
screen.blit(game_over_text, (screen_width // 2 - 150, screen_height // 2))
pygame.display.update()

# 延迟退出游戏
pygame.time.wait(2000)

# 退出游戏
pygame.quit()

请注意，这只是一个简单的示例代码，游戏中可能还有许多不完善的地方。你可以根据自己的需求进行修改和优化。此外，你还需要准备飞机、背景、子弹、敌机的图像和音效文件，并将它们与代码放在同一目录下。然后，你可以使用Python解释器来运行代码并开始游戏。