gameTest.py

import sys
import pygame

clock = pygame.time.Clock()
pygame.init()
display = pygame.display


def main():
    display.set_caption("Don't Let It Fall")
    size = width, height = 320, 240
    speed = [2, 2]
    black = 0, 0, 0

    screen = pygame.display.set_mode(size)

    ball = pygame.image.load("intro_ball.gif")
    default_image_size = (45, 45)
    ball = pygame.transform.scale(ball, default_image_size)
    ballrect = ball.get_rect()

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

        ballrect = ballrect.move(speed)
        if ballrect.left < 0 or ballrect.right > width:
            speed[0] = -speed[0]
        if ballrect.top < 0 or ballrect.bottom > height:
            speed[1] = -speed[1]

        screen.fill(black)
        screen.blit(ball, ballrect)
        pygame.display.flip()
        clock.tick(60)


if __name__ == '__main__':
    main()