PyGamePrimer.py

import pygame
import random

from pygame.locals import *


class Player(pygame.sprite.Sprite):
    def __init__(self):
        super(Player, self).__init__()
        self.surf = pygame.Surface((75, 25))
        self.surf.fill((255, 255, 255))
        self.rect = self.surf.get_rect()

    def update(self, pressed_keys):
        if pressed_keys[K_UP]:
            self.rect.move_ip(0, -5)
        if pressed_keys[K_DOWN]:
            self.rect.move_ip(0, 5)
        if pressed_keys[K_LEFT]:
            self.rect.move_ip(-5, 0)
        if pressed_keys[K_RIGHT]:
            self.rect.move_ip(5, 0)

        # Keep player on the screen
        if self.rect.left < 0:
            self.rect.left = 0
        elif self.rect.right > 800:
            self.rect.right = 800
        if self.rect.top <= 0:
            self.rect.top = 0
        elif self.rect.bottom >= 600:
            self.rect.bottom = 600


class Enemy(pygame.sprite.Sprite):
    def __init__(self):
        super(Enemy, self).__init__()
        self.surf = pygame.Surface((20, 10))
        self.surf.fill((255, 255, 255))
        self.rect = self.surf.get_rect(center=(820, random.randint(0, 600)))
        self.speed = random.randint(5, 20)

    def update(self):
        self.rect.move_ip(-self.speed, 0)
        if self.rect.right < 0:
            self.kill()

pygame.init()

screen = pygame.display.set_mode((800, 600))

player = Player()


running = True

while running:
    for event in pygame.event.get():
        if event.type == KEYDOWN:
            if event.key == K_ESCAPE:
                running = False
        elif event.type == QUIT:
            running = False

    pressed_keys = pygame.key.get_pressed()

    player.update(pressed_keys)

    #screen.blit(player.surf, (400, 300))
    screen.blit(player.surf, player.rect)
    pygame.display.flip()