Sprite Manipulation

import pygame,random


class Player(pygame.sprite.Sprite):
    def __init__(self, *groups):
        super(Player, self).__init__(*groups)
        self.image = pygame.image.load('player.png')
        self.rect = pygame.rect.Rect((screen_width, (random.randrange(0,screen_height))), self.image.get_size())
        self.dx = -10
        self.pos = random.randrange(0,screen_height)

    def update(self):
       self.rect.centerx += self.dx

       if self.rect.right < 0:
           self.kill()



class Game(object):
    def main(self, screen):
        clock = pygame.time.Clock()

        sprites = pygame.sprite.Group()
        self.player = Player(sprites)

        while 1:
            clock.tick(30)

            for event in pygame.event.get():
                if event.type == pygame.QUIT:
                    return
                if event.type == pygame.KEYDOWN and event.key == pygame.K_ESCAPE:
                    return



            sprites.update()
            screen.fill((200, 200, 200))
            sprites.draw(screen)

            drone = Player()
            self.y = random.randrange(0,screen_height)
            sprites.add(drone)

            pygame.display.flip()

if __name__ == '__main__':
    pygame.init()
    screen_width = 640
    screen_height = 480
    screen = pygame.display.set_mode((screen_width, screen_height))
    Game().main(screen)