import pygame
import random



pygame.init()

width,height=900,500
screen=pygame.display.set_mode((width,height))




vel=0.1

def main():

    player1=pygame.Rect(5,height//2-20,10,40)
    player2=pygame.Rect(0,height//2-20,10,40)
    player2=pygame.Rect(width-5-player2.width,height//2-20,10,40)
    

    go=random.randint(0,1)




    while True:
        for event in pygame.event.get():
            if event.type==pygame.QUIT:
                exit()
            
    
        screen.fill((0,0,0))
        pygame.draw.rect(screen,(255,255,255),player1)
        pygame.draw.rect(screen,(255,255,255),player2)
        key=pygame.key.get_pressed()

        if key[pygame.K_UP] and player2.y-vel>0:
            player2.y-=vel
        if key[pygame.K_DOWN] and player2.y+vel+player2.height<height:
            player2.y+=vel

        pygame.display.flip()
if __name__=="__main__":
    main()

here is my code. you can see velocity is 1 and min, but it’s run too fast, I don’t know how to make it slower although pygame will round player2.y so I can use float

I tried float but it didn’t work. pygame will round it. If you use 0.5 you will only go down not up