SFd

import pygame
import random

WIDTH, HEIGHT = 600, 700
WHITE = (255, 255, 255)
BLUE = (0,100,200)
RAIN_DENSITY = 50
dropList = []
canvas = pygame.display.set_mode((WIDTH,HEIGHT))
background  = pygame.Surface((WIDTH,HEIGHT))
pygame.display.set_caption('Rain')
pygame.init()

def quitGame():
    pygame.quit()
    sys.exit(0)

for i in range(RAIN_DENSITY):
    x = random.randint(0, WIDTH-2)
    y = random.randint(-700, -10)
    speed = random.randint(2, 3)
    dropList.append([x, y, speed])

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            quitGame()

    canvas.blit(background, (0,0))
    for i in dropList:
        i[1] += i[2]
        drop = (i[0], i[1], 2, 20)
        pygame.draw.rect(canvas, BLUE, drop, 2)

        if i[1] > HEIGHT:
            i[0] = random.randint(0, WIDTH-2)
            i[1] = random.randint(-50, -10)
            i[2] = random.randint(2,3)

    pygame.display.flip()