准备工作：下载python，比如Anaconda3（64 bit），导入pygame游戏包

1.外星人设置，alien.py，代码：

import pygame
from pygame.sprite import Sprite

class Alien(Sprite):
    """表示单个外星人的类"""
    
    def __init__(self,ai_settings,screen):
        """初始化外星人并设置其他位置"""
        super(Alien,self).__init__()
        self.screen = screen
        self.ai_settings = ai_settings
        
        #加载外星人图像，并设置其rect属性
        self.image = pygame.image.load('images/alien.bmp')
        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):
        """如果外星人位于屏幕边缘，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):
        """向右移动外星人"""
        self.x += (self.ai_settings.alien_speed_factor * self.ai_settings.fleet_direction)
        self.rect.x = self.x

2.游戏主程序，alien_invasion.py，代码:

import pygame

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

def run_game():
    pygame.init()       # 初始化背景设置
    ai_settings = Settings()        # 全局设置

    screen = pygame.display.set_mode(           # 创建screen显示窗口
        (ai_settings.screen_width,ai_settings.screen_height)
    )
    pygame.display.set_caption('Alien Invasion')    # 标题
    #新建Play按钮
    play_button = Button(ai_settings,screen,"Play")
    #创建一个用于存储游戏统计信息的实例,并创建记分牌
    stats = GameStats(ai_settings)
    sb = Scoreboard(ai_settings, screen, stats)
    # 创建飞船
    ship = Ship(ai_settings,screen)
    # 创建子弹编组
    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:
            # 移动飞船
            gf.update_ship(ship)
            # 更新子弹位置
            gf.update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets)
            #更新外星人
            gf.update_aliens(ai_settings,stats,screen,sb,ship,aliens,bullets)
        # 更新屏幕
        gf.update_screen(ai_settings,screen,stats,sb,ship,aliens,bullets,play_button)

run_game()

3.设置子弹，bullet.py，代码：

import pygame
from pygame.sprite import Sprite
import time

class Bullet(Sprite):
    '''飞船子弹进行管理'''

    def __init__(self,ai_settings,screen,ship):
        super(Bullet,self).__init__()
        self.screen = screen

        # 创建子弹矩形初始位置（0,0,3,15）分别对应lef，top，宽，高
        self.rect = pygame.Rect(0,0,
        ai_settings.bullet_width, ai_settings.bullet_height)

        self.rect.centerx = ship.rect.centerx  # 设置中心点x轴坐标跟飞船一致
        self.rect.top = ship.rect.top          # 设置y轴坐标顶部跟飞船一致

        # 设置成小数进行计算
        self.top = float(self.rect.top)

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

    def update(self):
        self.top -=self.speed_factor
        self.rect.top = self.top
        print(self.rect.top)

    def draw_bullet(self):
        pygame.draw.rect(self.screen,self.color,self.rect)

4.设置Play按钮，button.py，代码：

import pygame.font

class Button():
    
    def __init__(self,ai_settings,screen,msg):
        """初始化按钮属性"""
        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 = (0,255,0)
        self.text_color = (255,255,255)
        self.font = pygame.font.SysFont(None,48)
        
        #创建按钮的rect对象，并使其居中
        self.rect = pygame.Rect(0,0,self.width,self.height)
        self.rect.center = self.screen_rect.center
        
        #按钮的标签只需创建一次
        self.prep_msg(msg)
        
    def prep_msg(self,msg):
        """将msg渲染为图像，并使其在按钮上居中"""
        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)

5.设置游戏功能，game_functions.py，代码：

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

def check_events(ai_settings,screen,stats,sb,play_button,ship,aliens,bullets):
    # 监视键盘和鼠标事件
    for event in pygame.event.get():

        if event.type == pygame.QUIT:  # 关闭窗口退出
            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):
    """在玩家单击Play按钮时开始游戏"""
    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)
        #重置游戏统计信息
        stats.reset_stats()
        stats.game_active = True
        
        #重置计分牌图像
        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):
    '''更新屏幕上的图片，并切换到新屏幕'''
    screen.fill(ai_settings.bg_color)  # 设置背景颜色
    ship.blitme()  # 绘制飞船
    aliens.draw(screen)
    # 循环子弹组里面的元素，进行绘制 为空时不执行
    for bullet in bullets.sprites():
        bullet.draw_bullet()    # 绘制子弹
    #显示得分
    sb.show_score()
    #如果游戏处于非活跃状态，就显示Play按钮
    if not stats.game_active:
        play_button.draw_button()
    # 显示最新屏幕，擦拭旧屏幕
    pygame.display.flip()
    # print('1')

def check_keydown_events(event,ai_settings,screen,ship,bullets):
    if event.key == pygame.K_RIGHT:
        ship.moving_right = True
    elif event.key == pygame.K_LEFT:
        ship.moving_left = True
    elif event.key == pygame.K_SPACE:
        fire_bullet(ai_settings,screen,ship,bullets)
    elif event.key == pygame.K_q:
        sys.exit()

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

def update_bullets(ai_settings,screen,stats,sb,ship,aliens,bullets):
    '''更新子弹位置，删除子弹'''
    bullets.update()     # 子弹组每个成员执行self.update()操作
    for bullet in bullets.sprites():
        if bullet.rect.bottom <= 0:  # 子弹出界 删除
            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):  
    """响应外星人和子弹的碰撞"""
    #删除发生碰撞的子弹和外星人
    collisions = pygame.sprite.groupcollide(bullets,aliens,True,True)
    
    if collisions:
        for aliens in collisions.values(): 
            stats.score += ai_settings.alien_points * len(aliens)
            sb.prep_score()
        check_high_score(stats,sb)
        
    if len(aliens)==0:
        #删除现有的子弹并新建一群外星人,加快游戏进度节奏
        bullets.empty()
        ai_settings.increase_speed()
        
        #提高等级
        stats.level += 1
        sb.prep_level()
        
        create_fleet(ai_settings,screen,ship,aliens)

def update_ship(ship):
    ship.update()

def fire_bullet(ai_settings,screen,ship,bullets):
    # 创建一个子弹对象 加入到子弹组
    if len(bullets) < ai_settings.bullets_allowed:  # 子弹少于允许值时再生成
        new_bullet = Bullet(ai_settings, screen, ship)
        bullets.add(new_bullet)

def get_number_aliens_x(ai_settings,alien_width):
    """计算每行可容纳多少个外星人"""
    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 get_number_rows(ai_settings,ship_height,alien_height):
    """计算屏幕可容纳多少行外星人"""
    available_space_y = (ai_settings.screen_height - (3 * alien_height) - ship_height)
    number_rows = int(available_space_y / (2 * alien_height))
    return number_rows
    
def create_aliens(ai_settings,screen,aliens,alien_number,row_number):
    """创建一个外星人并将其放在当期行"""
    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 create_fleet(ai_settings,screen,ship,aliens):
    """创建外星人群"""
    #创建一个外星人，并计算一行可以容纳多少个外星人
    #外星人间距为外星人宽度
    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
            create_aliens(ai_settings,screen,aliens,alien_number,row_number)
 
def check_fleet_edges(ai_settings,aliens):
    """有外星人到达边缘时采取相应措施"""
    for alien in aliens.sprites():
        if alien.check_edges():
            change_fleet_direction(ai_settings,aliens)
            break
        
def change_fleet_direction(ai_settings,aliens):
    """将整群外星人下移，并改变他们的运动方向"""
    for alien in aliens.sprites():
        alien.rect.y += ai_settings.fleet_drop_speed
    ai_settings.fleet_direction *= -1

def ship_hit(ai_settings,stats,screen,sb,ship,aliens,bullets):
    """响应被外星人撞到的飞船"""
    if stats.ships_left > 0:
        #将ship_left减1
        stats.ships_left -= 1
        
        #更新记分牌
        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，并将飞船放到屏幕低端中央
        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,stats,screen,sb,ship,aliens,bullets):
    """检查是否有外星人到达屏幕低端"""
    screen_rect = screen.get_rect()
    for alien in aliens.sprites():
        if alien.rect.bottom >= screen_rect.bottom:
            #像飞船被撞到一样进行处理
            ship_hit(ai_settings,stats,screen,sb,ship,aliens,bullets)
            break

             
def update_aliens(ai_settings,stats,screen,sb,ship,aliens,bullets):
    """更新外星人群中所有外星人的位置"""
    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,stats,screen,sb,ship,aliens,bullets)
    #检查是否有外星人到达屏幕低端
    check_aliens_bottom(ai_settings,stats,screen,sb,ship,aliens,bullets)

def check_high_score(stats,sb):
    """检查是否诞生了新的最高纪录"""
    if stats.score > stats.high_score:
        stats.high_score = stats.score
        sb.prep_high_score()

6.游戏统计信息，game_stats.py，代码：

class GameStats():
    """跟踪游戏的统计信息"""
    def __init__(self,ai_settings):
        """初始化统计信息"""
        self.ai_settings = ai_settings
        self.reset_stats()
        #游戏刚启动时处于非活动状态
        self.game_active = False
        #在任何情况下不应该重置最高分
        self.high_score = 0
        self.level = 1
        
    def reset_stats(self):
        """初始化在游戏运行期间可能变化的统计信息"""
        self.ships_left = self.ai_settings.ship_limit
        self.score = 0

7.分数设置，scoreboard.py，代码：

import pygame.font
from pygame.sprite import Group

from ship import Ship

class Scoreboard():
    """显示得分信息的类"""
    
    def __init__(self, ai_settings, screen, stats):
        """初始化显示得分涉及的属性"""
        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)
        
        #准备初始化得分图像和当前最高分数
        self.prep_score()
        self.prep_high_score()
        self.prep_level()
        self.prep_ships()
        
    def prep_score(self):
        """将得分转换为一幅渲染的图像"""
        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)
        
        #将得分放在右上角
        self.score_rect = self.score_image.get_rect()
        self.score_rect.right = self.screen_rect.right - 20
        self.score_rect.top = 5
    
    def prep_high_score(self):
        """将最高得分转换为渲染图像"""
        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)
        
        #将最高分放在屏幕最中央
        self.high_score_rect = self.high_score_image.get_rect()
        self.high_score_rect.centerx = self.screen_rect.centerx
        self.high_score_rect.top = 5
        
    def prep_level(self):
        """将等级转换为渲染图像"""
        self.level_image = self.font.render(str(self.stats.level), True, self.text_color, self.ai_settings.bg_color)
        
        #将得分放在右上角
        self.level_rect = self.score_image.get_rect()
        self.level_rect.right = self.screen_rect.right
        self.level_rect.top = self.score_rect.bottom 
        
    def prep_ships(self):
        """显示还剩下多少艘飞船"""
        self.ships = Group()
        for ship_number in range(self.stats.ships_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)
        
    def show_score(self):
        """在屏幕上显示得分和等级"""
        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)
        #绘制飞船
        self.ships.draw(self.screen)
        

8.设置，settings.py，代码：

class Settings():
    '''存储外星人入侵中所有的设置'''

    def __init__(self):
        '''初始化设置'''
        #屏幕设置
        self.screen_width = 1200
        self.screen_height = 600
        self.bg_color = (230,230,230)    # 设置背景色  灰色
        
        #飞船设置
        self.ship_limit = 3
        self.ship_image_path = 'images/ship.bmp'    # 飞船图片路径
        
        #子弹设置
        self.bullet_width = 3
        self.bullet_height = 15
        self.bullet_color = 60,60,60
        self.bullets_allowed = 3         # 允许屏幕中出现子弹的数量
        
        #外星人设置
        self.fleet_drop_speed = 10
        
        
        #以什么样的速度加快游戏节奏
        self.speedup_scale = 1.1
        #外星人点数提高速度
        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表示向右移，为-1表示向左移
        self.fleet_direction = 1
        
        #计分
        self.alien_points = 50
        
    def increase_speed(self):
        """提高速度设置,外星人点数"""
        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)
        

9.飞船设置，ship.py，代码：

import pygame
from pygame.sprite import Sprite

class Ship(Sprite):
    '''飞船所有信息'''

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

        # 加载飞船图片、获取外接矩形
        self.image = pygame.image.load(self.ai_settings.ship_image_path)   # 加载图片
        self.image = pygame.transform.smoothscale(self.image,(40,60))
        self.rect = self.image.get_rect()   # 获取图片外接矩形
        self.screen_rect = screen.get_rect()        #获取屏幕外接矩形

        # 将每搜新飞船放到并木底部中心
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom
        # 设置成浮点类型
        self.center = float(self.rect.centerx)      # self.rect.centerx设置不了浮点数 只能另设置一个变量进行运算

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

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

    def update(self):
        # 向右移动飞船
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.center +=self.ai_settings.ship_speed_factor
        # 向左移动飞船
        if self.moving_left and self.rect.left > self.screen_rect.left:
            self.center -= self.ai_settings.ship_speed_factor

        self.rect.centerx = self.center

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