我测试了一下，问题是你在每个循环中都创建了新的雨滴，因为你在循环中有self._create_fleet()。你必须在循环之前使用它来创建第一个雨滴。

def run_game(self):
    clock = pygame.time.Clock()

    self._create_fleet()

    while True:
        self._update_screen()
        self.check_events()
        self._update_raindrops()

        clock.tick(25)  # the same speed 25 FPS (Frames Per Seconds) on old and new computers

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编辑：

我的版本与其他一些变化

• 我使用Clock()总是25 FPS
• 我不检查是否雨滴离开屏幕在顶部
• 我检查如果顶部的雨滴（不是底部的raindrom）离开屏幕，所以它看起来更好
• 我不移走雨滴，而是移到顶部

的数据

import os
import pygame

APP_HOME = os.path.dirname(os.path.abspath(__file__))

class Settings():
    screen_width = 800
    screen_height = 600
    raindrop_speed = 5

    
class Raindrop(pygame.sprite.Sprite):
    """Class to manage raindrops"""

    def __init__(self, ai_game):
        super().__init__()
        self.settings = ai_game.settings
        self.screen = ai_game.screen
        self.image = pygame.image.load(os.path.join(APP_HOME, 'images', 'raindrop.bmp')).convert_alpha()
        self.rect = self.image.get_rect()
        self.rect.y = self.rect.height
        self.y = float(self.rect.y)

    def check_edges(self):
        screen_rect = self.screen.get_rect()
        #if self.rect.bottom >= screen_rect.bottom or self.rect.top <= 0:
        #    return True
        
        # check only bottom edge
        # and use `top` instead of `botton` check when full dropdown leaves screen
        if self.rect.top >= screen_rect.bottom:
            return True

    def update(self):
        """Move the raindrop down."""
        self.y += self.settings.raindrop_speed
        self.rect.y = self.y

    def blitme(self):
        self.screen.blit(self.image, self.rect)

class RaindropsGame:
    """Overall class to manage game"""

    def __init__(self):
        pygame.init()
        self.settings = Settings()
        self.screen = pygame.display.set_mode((self.settings.screen_width, self.settings.screen_height))
        self.raindrops = pygame.sprite.Group()
        self.screen_caption = pygame.display.set_caption("Raindrops")
        self.BackGround = pygame.image.load(os.path.join(APP_HOME, 'images', 'clouds.bmp'))

    def run_game(self):
        clock = pygame.time.Clock()
        self._create_fleet()
        while True:
            self._update_screen()
            self.check_events()
            self._update_raindrops()
            clock.tick(25)  # 25 FPS

    def _update_screen(self):
        self.screen.blit(self.BackGround, (0, 0))
        self.raindrops.draw(self.screen)
        pygame.display.flip()

    def _update_raindrops(self):
        self._check_fleet_edges()
        self.raindrops.update()
        if not self.raindrops:
            self._create_fleet()

    def check_events(self):
        """Check keyboard key presses and mouse events."""
        for event in pygame.event.get():
            if event.type == pygame.QUIT:
                exit()
            elif event.type == pygame.KEYDOWN:
                if event.key == pygame.K_q:
                    exit()

    def _create_raindrop(self, column_number, row_number):
        raindrop = Raindrop(self)
        raindrop_width, raindrop_height = raindrop.rect.size
        
        raindrop.x = (1.1 * raindrop_width) * column_number
        raindrop.rect.x = raindrop.x
        
        raindrop.y = (1.2 * raindrop_height) * row_number
        raindrop.rect.y = raindrop.y
        
        self.raindrops.add(raindrop)

    def _create_fleet(self):
        raindrop = Raindrop(self)
        raindrop_width, raindrop_height = raindrop.rect.size
        
        available_space_x = self.settings.screen_width - (2 * raindrop_width)
        number_raindrops_x = available_space_x // (1 * raindrop_width)
        
        available_space_y = self.settings.screen_height - (5 * raindrop_height)
        number_rows = available_space_y // (1 * raindrop_height)
        
        for row_number in range(number_rows):
            for raindrop_number in range(number_raindrops_x):
                self._create_raindrop(raindrop_number, row_number)
                
    def _check_fleet_edges(self):
        for raindrop in self.raindrops.sprites():
            if raindrop.check_edges():
                #self.raindrops.remove(raindrop)
                
                # move to top instead of removing
                raindrop.rect.bottom = 0
                raindrop.y = raindrop.rect.y
                
if __name__ in '__main__':
    ai = RaindropsGame()
    ai.run_game()

型
图片：
clouds.bmp个

的
raindrop.bmp个

的