gravity

import pygame, sys, os
from pygame.locals import *
#init
pygame.init()
height = 200;
width = 200;

screen = pygame.display.set_mode((height, width))
pygame.display.set_caption("Gravity port")

#variables
plx = 90;
ply = 0;
speed = 0;
gravity = 0.1;


player = pygame.image.load(os.path.join("player.png"))
player.convert()
clock = pygame.time.Clock()

while True:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
    if plx < 0:
        plx = 0
    screen.fill((4, 6, 3))
    screen.blit(player, (plx, ply))
    ply = ply + speed;
    speed = speed + gravity;
    if (ply > height):
        speed = speed * -0.95;
    pygame.display.flip()
    clock.tick(50)
pygame.quit()