T2 = pygame.time.get_ticks()
    all_sprites.update()

    if c is 0:
        if T2 - T1 > 2000:
            m = Mob()
            c = 1
            d = 0
            all_sprites.add(m)
            mobs.add(m)
    if d is 0:
        if T2 - T1 > 8000:
            T1 = T2
            c = 0
            m.kill()
    else:
        if T2 - T1 > 13000:
            T1 = T2
            c = 0
            m.kill()
    fits = pygame.sprite.groupcollide(mobs, lifers, False, True)
    for fit in fits:
        d = 1
        fit.image = pygame.transform.scale(change_img, (60, 60))
        fit.image.set_colorkey(BLACK)
    hits = pygame.sprite.groupcollide(mobs, bullets, True, True)
    for hit in hits:
        score += 10
        T1 = T2
        c = 0