text: import pygame
  import os
  import time
  import random
  pygame.font.init()
  
  WIDTH, HEIGHT = 650, 650
  WIN = pygame.display.set_mode((WIDTH, HEIGHT))
  pygame.display.set_caption("Earth vs. Invaders")
  
  # Load images
  RED_SPACE_SHIP = pygame.image.load(os.path.join("assets", "pixel_ship_red_small.png"))
  GREEN_SPACE_SHIP = pygame.image.load(os.path.join("assets", "pixel_ship_green_small.png"))
  BLUE_SPACE_SHIP = pygame.image.load(os.path.join("assets", "pixel_ship_blue_small.png"))
  
  # Player player
  YELLOW_SPACE_SHIP = pygame.image.load(os.path.join("assets", "pixel_ship_yellow.png"))
  
  # Lasers
  RED_LASER = pygame.image.load(os.path.join("assets", "pixel_laser_red.png"))
  GREEN_LASER = pygame.image.load(os.path.join("assets", "pixel_laser_green.png"))
  BLUE_LASER = pygame.image.load(os.path.join("assets", "pixel_laser_blue.png"))
  YELLOW_LASER = pygame.image.load(os.path.join("assets", "pixel_laser_yellow.png"))
  
  # Background
  BG = pygame.transform.scale(pygame.image.load(os.path.join("assets", "background-black.png")), (WIDTH, HEIGHT))
  
  class Laser:
      def __init__(self, x, y, img):
          self.x = x
          self.y = y
          self.img = img
          self.mask = pygame.mask.from_surface(self.img)
  
      def draw(self, window):
          window.blit(self.img, (self.x, self.y))
  
      def move(self, vel):
          self.y += vel
  
      def off_screen(self, height):
          return not(self.y <= height and self.y >= 0)
  
      def collision(self, obj):
          return collide(self, obj)
  
  
  class Ship:
      COOLDOWN = 30
  
      def __init__(self, x, y, health=100):
          self.x = x
          self.y = y
          self.health = health
          self.ship_img = None
          self.laser_img = None
          self.lasers = []
          self.cool_down_counter = 0
  
      def draw(self, window):
          window.blit(self.ship_img, (self.x, self.y))
          for laser in self.lasers:
              laser.draw(window)
  
      def move_lasers(self, vel, obj):
          self.cooldown()
          for laser in self.lasers:
              laser.move(vel)
              if laser.off_screen(HEIGHT):
                  self.lasers.remove(laser)
              elif laser.collision(obj):
                  obj.health -= 10
                  self.lasers.remove(laser)
  
      def cooldown(self):
          if self.cool_down_counter >= self.COOLDOWN:
              self.cool_down_counter = 0
          elif self.cool_down_counter > 0:
              self.cool_down_counter += 1
  
      def shoot(self):
          if self.cool_down_counter == 0:
              laser = Laser(self.x, self.y, self.laser_img)
              self.lasers.append(laser)
              self.cool_down_counter = 1
  
      def get_width(self):
          return self.ship_img.get_width()
  
      def get_height(self):
          return self.ship_img.get_height()
  
  
  class Player(Ship):
      def __init__(self, x, y, health=100):
          super().__init__(x, y, health)
          self.ship_img = YELLOW_SPACE_SHIP
          self.laser_img = YELLOW_LASER
          self.mask = pygame.mask.from_surface(self.ship_img)
          self.max_health = health
  
      def move_lasers(self, vel, objs):
          self.cooldown()
          for laser in self.lasers:
              laser.move(vel)
              if laser.off_screen(HEIGHT):
                  self.lasers.remove(laser)
              else:
                  for obj in objs:
                      if laser.collision(obj):
                          objs.remove(obj)
                          if laser in self.lasers:
                              self.lasers.remove(laser)
  
      def draw(self, window):
          super().draw(window)
          self.healthbar(window)
  
      def healthbar(self, window):
          pygame.draw.rect(window, (255,0,0), (self.x, self.y + self.ship_img.get_height() + 10, self.ship_img.get_width(), 10))
          pygame.draw.rect(window, (0,255,0), (self.x, self.y + self.ship_img.get_height() + 10, self.ship_img.get_width() * (self.health/self.max_health), 10))
  
  
  class Enemy(Ship):
      COLOR_MAP = {
                  "red": (RED_SPACE_SHIP, RED_LASER),
                  "green": (GREEN_SPACE_SHIP, GREEN_LASER),
                  "blue": (BLUE_SPACE_SHIP, BLUE_LASER)
                  }
  
      def __init__(self, x, y, color, health=100):
          super().__init__(x, y, health)
          self.ship_img, self.laser_img = self.COLOR_MAP[color]
          self.mask = pygame.mask.from_surface(self.ship_img)
  
      def move(self, vel):
          self.y += vel
  
      def shoot(self):
          if self.cool_down_counter == 0:
              laser = Laser(self.x-20, self.y, self.laser_img)
              self.lasers.append(laser)
              self.cool_down_counter = 1
  
  
  def collide(obj1, obj2):
      offset_x = obj2.x - obj1.x
      offset_y = obj2.y - obj1.y
      return obj1.mask.overlap(obj2.mask, (offset_x, offset_y)) != None
  
  def main():
      run = True
      FPS = 60
      level = 0
      lives = 5
      main_font = pygame.font.SysFont("comicsans", 40)
      lost_font = pygame.font.SysFont("comicsans", 50)
  
      enemies = []
      wave_length = 5
      enemy_vel = 1
  
      player_vel = 5
      laser_vel = 5
  
      player = Player(300, 530)
  
      clock = pygame.time.Clock()
  
      lost = False
      lost_count = 0
  
      def redraw_window():
          WIN.blit(BG, (0,0))
          # draw text
          lives_label = main_font.render(f"Lives: {lives}", 1, (255,255,255))
          level_label = main_font.render(f"Level: {level}", 1, (255,255,255))
  
          WIN.blit(lives_label, (10, 10))
          WIN.blit(level_label, (WIDTH - level_label.get_width() - 10, 10))
  
          for enemy in enemies:
              enemy.draw(WIN)
  
          player.draw(WIN)
  
          if lost:
              lost_label = lost_font.render("You Lost!!", 1, (255,255,255))
              WIN.blit(lost_label, (WIDTH/2 - lost_label.get_width()/2, 350))
  
          pygame.display.update()
  
      while run:
          clock.tick(FPS)
          redraw_window()
  
          if lives <= 0 or player.health <= 0:
              lost = True
              lost_count += 1
  
          if lost:
              if lost_count > FPS * 3:
                  run = False
              else:
                  continue
  
          if len(enemies) == 0:
              level += 1
              wave_length += 5
              for i in range(wave_length):
                  enemy = Enemy(random.randrange(50, WIDTH-100), random.randrange(-1500, -100), random.choice(["red", "blue", "green"]))
                  enemies.append(enemy)
  
          for event in pygame.event.get():
              if event.type == pygame.QUIT:
                  quit()
  
          keys = pygame.key.get_pressed()
          if keys[pygame.K_a] and player.x - player_vel > 0: # left
              player.x -= player_vel
          if keys[pygame.K_d] and player.x + player_vel + player.get_width() < WIDTH: # right
              player.x += player_vel
          if keys[pygame.K_w] and player.y - player_vel > 0: # up
              player.y -= player_vel
          if keys[pygame.K_s] and player.y + player_vel + player.get_height() + 15 < HEIGHT: # down
              player.y += player_vel
          if keys[pygame.K_SPACE]:
              player.shoot()
  
          for enemy in enemies[:]:
              enemy.move(enemy_vel)
              enemy.move_lasers(laser_vel, player)
  
              if random.randrange(0, 2*60) == 1:
                  enemy.shoot()
  
              if collide(enemy, player):
                  player.health -= 10
                  enemies.remove(enemy)
              elif enemy.y + enemy.get_height() > HEIGHT:
                  lives -= 1
                  enemies.remove(enemy)
  
          player.move_lasers(-laser_vel, enemies)
  
  def main_menu():
      title_font = pygame.font.SysFont("comicsans", 60)
      run = True
      while run:
          WIN.blit(BG, (0,0))
          title_label = title_font.render("Press the mouse to begin...", 1, (255,255,255))
          WIN.blit(title_label, (WIDTH/2 - title_label.get_width()/2, 250))
          pygame.display.update()
          for event in pygame.event.get():
              if event.type == pygame.QUIT:
                  run = False
              if event.type == pygame.MOUSEBUTTONDOWN:
                  main()
      pygame.quit()
  
  
  main_menu()