这是一个打飞机的游戏，结构如下：

其中images中包含的素材为

命名为alien.png

命名为ship.png

游戏效果运行是这样的：

敌军，也就是体型稍微大点的，在上方左右移动，并且有规律向下移动。我军目标，消灭所有飞机。但是屏幕上最多只展现3颗子弹。

一旦，我军飞机与敌军飞机碰撞，或者敌军飞机抵达底部。我军损失一条生命，一共三条。

敌军飞机全部消灭完，则到下一关，移动速度会更快。

我军每消灭一架敌军飞机获得积分，积分最高者会在界面显示。

游戏源码如下：

#alien_invasion.py  
#主程序文件

"""
创建Pygame窗口响应以及用户输入
"""


import pygame
from settings import Settings
from ship import Ship
import game_functions as gf
from pygame.sprite import Group
from alien import Alien
from game_stats import GameStats
from button import Button
from Scoreboard import Scoreboard


def run_game():
    
    #初始化游戏并且创建一个屏幕对象
    pygame.init()
    
    ai_settings = Settings()
    
    screen = pygame.display.set_mode(
        (ai_settings.screen_width, ai_settings.screen_height))
    
    pygame.display.set_caption("Alien Invasion")

    #创建play按钮
    play_button = Button(ai_settings, screen, "PLAY~")
    
    #创建一个用户存储游戏统计信息的实例
    stats = GameStats(ai_settings)

    sb = Scoreboard(ai_settings, screen, stats)

    #创建一艘飞船
    ship = Ship(ai_settings,screen)
    
    #创建一个用户存储子弹的编组
    bullets = Group()
    
    #创建一个外星人
    aliens = Group()

    #创建外星人群
    gf.create_fleet(ai_settings, screen,ship, aliens)


    #开始游戏主循环
    while True:
        
        #监视键盘和鼠标事件
        gf.check_events(ai_settings, screen, stats,sb, play_button, ship, aliens,bullets)
        
        if stats.game_active:
            ship.update()

        
            #删除已消失的子弹
            gf.update_bullets(ai_settings, screen, stats, sb, ship, aliens, bullets)

            gf.update_aliens(ai_settings, screen, stats, sb, ship, aliens, bullets)

        gf.update_screen(ai_settings, screen,stats, sb, ship, aliens, bullets, play_button)

        #让最近绘制的屏幕可见
        pygame.display.flip()

run_game()

#alien.py

import pygame
from pygame.sprite import Sprite


class Alien(Sprite):
    def __init__(self,ai_settings, screen ):
        """初始化外星人并且设置起始位置"""
        super().__init__()
        self.screen = screen
        self.ai_settings = ai_settings

        #加载外星人图像，并且设置其rect属性
        self.image = pygame.image.load("images/alien.png")
        self.rect = self.image.get_rect()

        #每个外星人最初都在屏幕左上角附近
        self.rect.x = self.rect.width
        self.rect.y = self.rect.height

        #存储外星人的准确位置
        self.x = float(self.rect.x)


    def blitme(self):
        """在指定位置绘制外星人"""
        self.screen.blit(self.image, self.rect)

    def check_edges(self):
        """如果外星人出于屏幕边缘，就返回True"""
        screen_rect = self.screen.get_rect()
        if self.rect.right >=  screen_rect.right:
            return True
        elif self.rect.left <= 0:
            return True

    def update(self):
        """向左或者右移动的外星人"""
        self.x += (self.ai_settings.alien_speed_factor * 
            self.ai_settings.fleet_direction)
        self.rect.x = self.x

#bullet.py


import pygame
from   pygame.sprite   import Sprite  

class Bullet(Sprite):
    """一个对飞船发射的子弹进行管理的类"""
    """Bullet类继承了我们从模块pygame.sprite中导入的Sprite类"""

    def __init__(self, ai_settings, screen, ship):
        """在飞船所处的位置创建一个子弹对象"""

        """为创建子弹实例，需要向__init__()传递
        ai_settings、screen和ship实例，还调用了super()来继承Sprite。
        """
        super().__init__()
        self.screen = screen

        """
        在（0.0）处创建一个表示子弹的矩形，再设置正确的位置
        我们创建了子弹的属性rect。子弹并非基于图像的，因此我们必须使用pygame.Rect()
        类从空白开始创建一个矩形
        """
        self.rect = pygame.Rect(
            0,0,ai_settings.bullet_width,ai_settings.bullet_height)
        self.rect.centerx = ship.rect.centerx  #将子弹的centerx设置为飞船的rect.centerx
        self.rect.top = ship.rect.top         #子弹的rect的top属性设置为飞船的rect的top属性


        #存储用小数表示的子弹位置
        self.y = float(self.rect.y)

        self.color = ai_settings.bullet_color
        self.speed_factor = ai_settings.bullet_speed_factor


    def update(self):
        """向上移动子弹"""
        #更新表示移动子弹的位置的小数值
        self.y -= self.speed_factor
        #更新表示子弹的rect的位置
        self.rect.y = self.y

    def draw_bullet(self):
        """在屏幕上绘制子弹"""
        pygame.draw.rect(self.screen, self.color, self.rect)

#button.py


import pygame.font

class Button():
    def __init__(self, ai_settings, screen, msg):
        """初始化按钮的属性"""
        self.screen = screen
        self.screen_rect = screen.get_rect()

        #设置按钮的尺寸和其他属性
        self.width, self.height = 200, 50
        self.button_color = (0, 250, 0)
        self.text_color = (255, 255, 255)
        self.font = pygame.font.SysFont(None, 48)

        #创建按钮的rect对象，并且让它居中
        self.rect = pygame.Rect(0, 0, self.width, self.height)
        self.rect.center = self.screen_rect.center


        #按钮的标签只需要创建一次
        self.prep_msg(msg)

    
    def prep_msg(self, msg):

        self.msg_image = self.font.render(msg, True, self.text_color,self.button_color)
        self.msg_image_rect = self.msg_image.get_rect()
        self.msg_image_rect.center = self.rect.center

    def draw_button(self):
        # 绘制一个用颜色填充的按钮，再绘制文本
        self.screen.fill(self.button_color, self.rect)
        self.screen.blit(self.msg_image, self.msg_image_rect)

#game_functions.py


import sys
import pygame
from bullet import Bullet
from alien import Alien
from time import sleep

def check_keydown_events(event, ai_settings,screen,ship,bullets):
    """响应按键"""
    if event.key == pygame.K_RIGHT:
        #向右→移动
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        #向左移动
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        # 创建一颗子弹，并将其加入到编组bullets中
        fire_bullet(ai_settings, screen, ship, bullets)
    elif event.key == pygame.K_q:
        sys.exit()


def check_keyup_events(event, ship):
    """响应松开"""
    if event.key == pygame.K_RIGHT:
        ship.moving_right =  False
    elif event.key == pygame.K_LEFT:
        ship.moving_left =  False


def check_events(ai_settings, screen, stats,sb, play_button, ship, aliens,bullets):
    """响应和鼠标按键"""
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

        elif event.type == pygame.KEYDOWN:
            
            check_keydown_events(event, ai_settings, screen, ship, bullets)
        elif event.type ==  pygame.KEYUP:
            check_keyup_events(event, ship)
        elif event.type == pygame.MOUSEBUTTONDOWN:
            mouse_x,mouse_y = pygame.mouse.get_pos()
            check_play_button(ai_settings, screen, stats, sb, play_button, ship,aliens, bullets, mouse_x, mouse_y)

def check_play_button(
    ai_settings, screen, stats, sb, play_button, ship, aliens,bullets, mouse_x, mouse_y):
    
    button_clicked = play_button.rect.collidepoint(mouse_x, mouse_y)
    if button_clicked and not stats.game_active:
        # 重置游戏设置
        ai_settings.initialize_dynamic_settings()
        # 隐藏光标
        pygame.mouse.set_visible(False)
        #重置游戏
        stats.reset_start()
        stats.game_active = True

        #重置记分牌图像
        sb.prep_score()
        sb.prep_high_score()
        sb.prep_level()
        sb.prep_ships()


        # 清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()

        # 创建一群新的外星人，并让飞船居中
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()



def update_screen(ai_settings, screen, stats, sb, ship, aliens, bullets,play_button):
    """更新屏幕的图像，并且切换到新的屏幕"""
    #每次循环时都会重新绘屏
    screen.fill(ai_settings.bg_color)
    for bullet in bullets.sprites():
        bullet.draw_bullet()

    ship.blitme()
    aliens.draw(screen)
    #显示得分
    sb.show_score()
    
    # 如果游戏处于非活动状态，就绘制Play按钮
    if not stats.game_active:
        play_button.draw_button()

    #让最近绘制的屏幕可见
    pygame.display.flip()
def update_bullets(ai_settings, screen,stats, sb, ship, aliens, bullets):
    """更新子弹的位置，并且删除已消失的子弹
    在for循环中，不应从列表或编组中删除条目，因此必须遍历编组的副本。
    我们使用了方法copy()来设置for循环
    """
    bullets.update()
    for  bullet in bullets.copy():
        if bullet.rect.bottom <= 0:
            bullets.remove(bullet)
    check_bullet_alien_collisions(ai_settings, screen, stats, sb, ship, aliens, bullets)



def check_bullet_alien_collisions(
    ai_settings, screen, stats, sb, ship, aliens, bullets):
    #检查子弹是否打中飞机
    collisions = pygame.sprite.groupcollide(bullets, aliens, True, True)
    if len(aliens) == 0:
        #删除现有的子弹并新建一群外星人
        bullets.empty()
        ai_settings.increase_speed()  #新游戏加速
        #print(ai_settings.alien_speed_factor)
        create_fleet(ai_settings, screen, ship, aliens)

        stats.level += 1
        sb.prep_level()

    if collisions:
        for aliens in collisions.values():
            stats.score += ai_settings.alien_points * len(aliens)
            sb.prep_score()
        check_high_score(stats, sb)




def fire_bullet(ai_settings, screen, ship, bullets):
    """如果还没有到达限制，就发射一颗子弹"""
    #创建新子弹，并将其加入到编组bullets中
    if len(bullets) < ai_settings.bullets_allowed:
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)



def create_fleet(ai_settings, screen, ship, aliens):
    """创建外星人群"""
    #创建一个外星人并且计算一行可以容纳多少个外星人
    #外星人间距为外星人的宽度
    alien = Alien(ai_settings, screen)
    number_aliens_x = get_number_aliens_x(ai_settings,alien.rect.width)
    number_rows = get_number_rows(ai_settings, ship.rect.height, alien.rect.height)



    #创建第一行外星人
    for row_number in range(number_rows):

        for alien_number in  range(number_aliens_x):
            #创建一个外星人，并将其加入当前行列
            create_alien(ai_settings, screen, aliens, alien_number, row_number)



def get_number_aliens_x(ai_settings, alien_width):
    """计算每行可以容纳多少飞机"""
    available_space_x = ai_settings.screen_width - 2 * alien_width
    number_aliens_x = int(available_space_x / (2 * alien_width))
    return number_aliens_x



def create_alien(ai_settings, screen, aliens, alien_number, row_number):  #这里的row_number来自哪里？
    """创建一个外星人并把它放在当前行列"""
    alien = Alien(ai_settings, screen)
    alien_width = alien.rect.width
    alien.x = alien_width + 2 * alien_width * alien_number
    alien.rect.x = alien.x
    alien.rect.y = alien.rect.height + 2 * alien.rect.height * row_number
    aliens.add(alien)



def get_number_rows(ai_settings, ship_height, alien_hight):
    """计算屏幕可以容纳几行外星人"""
    available_space_y = (
        ai_settings.screen_height - (3*alien_hight) - ship_height)
    number_rows = int(available_space_y / (2*alien_hight))
    return number_rows


def update_aliens(ai_settings, screen, stats, sb, ship, aliens, bullets):
    """更新外星人的位置"""
    check_fleet_edges(ai_settings,aliens)
    aliens.update()

    #检测外星人和飞船之间的碰撞
    if pygame.sprite.spritecollideany(ship, aliens):
        ship_hit(ai_settings, screen, stats, sb, ship, aliens, bullets)

    check_aliens_bottom(ai_settings, screen, stats, sb, ship, aliens, bullets)


def check_fleet_edges(ai_settings, aliens):
    """有外星人撞到边缘时候采取的措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings, aliens)
            break



def change_fleet_direction(ai_settings,aliens):
    """整体外星人向下移动，并且改变方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1

def ship_hit(ai_settings, screen, stats, sb, ship, aliens, bullets):
    """响应被外星人撞到的飞船"""
    #ship_left -1
    if stats.ship_left > 0:
        stats.ship_left -=1

        #清空外星人列表和子弹列表
        aliens.empty()
        bullets.empty()

        sb.prep_ships()

        #创建一群新的外星人，并将飞船放到屏幕底端中央
        create_fleet(ai_settings, screen, ship, aliens)
        ship.center_ship()

        #暂停
        sleep(0.5)

    else:
        stats.game_active = False
        pygame.mouse.set_visible(True)


def check_aliens_bottom(ai_settings, screen, stats, sb, ship, aliens,
    bullets):
    """检查是否有外星人到达了屏幕底端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            #和飞船被撞处理一样
            ship_hit(ai_settings, screen, stats, sb, ship, aliens, bullets)
            break


def check_high_score(stats, sb):
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()

#game_stats.py


class GameStats():
    """游戏统计信息"""

    def __init__(self,ai_settings):
        """初始化统计信息"""
        self.ai_settings = ai_settings
        self.reset_start()
        #游戏一开始就是非活动状态
        self.game_active = False
        # 在任何情况下都不应重置最高得分
        self.high_score = 0

    def reset_start(self):
        """初始化在游戏运行期间可能变化的统计信息"""
        self.ship_left = self.ai_settings.ship_limit
        self.score = 0
        self.level = 1

#Scoreboard.py


import pygame.font
from pygame.sprite import Group
from ship import Ship


class Scoreboard():
    """显示信息得分的类"""

    def __init__(self, ai_settings, screen, stats):

        self.screen  = screen
        self.screen_rect = screen.get_rect()
        self.ai_settings = ai_settings
        self.stats = stats

        #显示得分信息时使用的字体设置
        self.text_color = (30, 30, 30)
        self.font = pygame.font.SysFont(None, 48)

        
        #准备初始得分图像 和最高得分

        self.prep_score()
        self.prep_high_score()
        self.prep_level()
        self.prep_ships()



    def prep_score(self):
        rounded_score = int(round(self.stats.score, -1))
        score_str = "{:,}".format(rounded_score)
        self.score_image = self.font.render(
            score_str,True, self.text_color, self.ai_settings.bg_color)

        #将得分放在屏幕右上角
        self.score_rect = self.score_image.get_rect()
        self.score_rect.right  = self.screen_rect.right -20
        self.score_rect.top = 20


    def show_score(self):
        self.screen.blit(self.score_image, self.score_rect)
        self.screen.blit(self.high_score_image, self.high_score_rect) 
        self.screen.blit(self.level_image, self.level_rect)
        self.ships.draw(self.screen)


    def prep_high_score(self):
        """渲染最高分为图像"""
        high_score = int(round(self.stats.high_score,-1))
        high_score_str = "{:,}".format(high_score)
        self.high_score_image = self.font.render(high_score_str, True,
            self.text_color, self.ai_settings.bg_color)

        #最高得分在顶部中央
        self.high_score_rect = self.high_score_image.get_rect()
        self.high_score_rect.centerx = self.screen_rect.centerx
        self.high_score_rect.top = self.screen_rect.top

    def prep_level(self):
        """将等级转换为渲染的图像"""
        self.level_image = self.font.render(str(self.stats.level), True, 
            self.text_color, self.ai_settings.bg_color)

        #位置
        self.level_rect = self.level_image.get_rect()
        self.level_rect.right = self.score_rect.right
        self.level_rect.top = self.score_rect.bottom + 10

    def prep_ships(self):

        self.ships = Group()
        for ship_number in range(self.stats.ship_left):
            ship = Ship(self.ai_settings, self.screen)
            ship.rect.x = 10 + ship_number * ship.rect.width
            ship.rect.y = 10
            self.ships.add(ship)

#settings.py



class Settings():
    """
    存储游戏所有设置的类
    """
    def __init__(self):
        """初始化游戏的设置"""
        #屏幕设置
        self.screen_width = 1200
        self.screen_height = 800
        self.bg_color = (230, 230, 230)
        # 飞船的设置
        self.ship_speed_factor = 1.5
        self.ship_limit = 3

        #子弹设置
        self.bullet_speed_factor = 3  
        self.bullet_width = 1    #这里更改子弹的宽度
        self.bullet_height = 15
        self.bullet_color = 60, 60, 60
        self.bullets_allowed = 300   #这里更改子弹的个数
        # 外星人设置

        self.fleet_drop_speed = 10         #默认10

        # 以什么样的速度加快游戏节奏
        self.speedup_scale = 1.1
        #分数的提高速度
        self.score_scale = 1.5

        self.initialize_dynamic_settings()


    def initialize_dynamic_settings(self):
        #初始化随游戏进行而变化的设置
        self.ship_speed_factor = 1.5
        self.bullet_speed_factor = 3
        self.alien_speed_factor = 1
        # fleet_direction为1表示向右；为-1表示向左
        self.fleet_direction = 1

        #积分
        self.alien_points = 50

    def increase_speed(self):
        #提高速度设置
        self.ship_speed_factor *= self.speedup_scale
        self.bullet_speed_factor *= self.speedup_scale
        self.alien_speed_factor *= self.speedup_scale
        self.alien_points = int(self.alien_points * self.score_scale)
        print(self.alien_points)

#ship.py



import pygame
from pygame.sprite import Sprite



class Ship(Sprite):

    def __init__(self, ai_settings, screen):
        """初始化飞船并设置其初始位置"""
        super(Ship, self).__init__()
        self.screen = screen
        self.ai_settings = ai_settings

        #加载飞船图像并获取其外接矩形
        self.image = pygame.image.load('images/ship.png')       #加载图像
        self.rect = self.image.get_rect()           #获取图像的大小
        self.screen_rect = screen.get_rect()        #获取窗口的大小

        #将新船放在屏幕底部中央位置
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom

        # 在飞船的属性center中存储小数值
        self.center = float(self.rect.centerx)

        #移动标志
        self.moving_right = False
        self.moving_left =   False

    def update(self):
        """根据移动标志调整飞船的位置"""
        # 更新飞船的center值，而不是rect
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.center += self.ai_settings.ship_speed_factor
        if self.moving_left and self.rect.left > 0:
            self.center -= self.ai_settings.ship_speed_factor
        # 根据self.center更新rect对象
        self.rect.centerx = self.center

    def blitme(self):
        """在指定位置绘制飞船"""
        self.screen.blit(self.image, self.rect)

    def center_ship(self):
        """让飞船在屏幕上居中"""
        self.center = self.screen_rect.centerx