Pygame

import pygame, sys

pygame.init()

screen = pygame.display.set_mode((720,576))
box = pygame.Rect(10,10,50,50)

while True:
  for event in pygame.event.get():
    if event.type == pygame.KEYDOWN and event.key == pygame.K_ESCAPE:
      sys.exit(0)

  keys = pygame.key.get_pressed()
  if keys[pygame.K_UP]:
    box.y -= 1
  if keys[pygame.K_DOWN]:
    box.y += 1
  if keys[pygame.K_LEFT]:
    box.x -= 1
  if keys[pygame.K_RIGHT]:
      box.x += 1

  screen.fill((0,0,0))
  pygame.draw.rect(screen, (211, 149, 247), box)
  pygame.display.flip()