mygame.py

import pygame

# Game variables
my_dudes_x_position = 300
bullets = []

window = pygame.display.set_mode((640, 480))
clock = pygame.time.Clock()

def clear_the_screen():
  pygame.draw.rect(window, (0,0,0), (0,0,640,480))

def draw_my_dude():
  pygame.draw.rect(window, (0, 255, 0), (my_dudes_x_position - 30, 400, 60, 20))

def draw_bullets():
  for bullet in bullets:
    pygame.draw.rect(window, (255, 0, 0), (bullet[0] - 2, bullet[1] - 2, 4, 4))

def draw_everything():
  clear_the_screen()
  draw_my_dude()
  draw_bullets()
  pygame.display.flip()

def move_bullets():
  for bullet in bullets:
    bullet[1] = bullet[1] - 1

running = True
while running:
  clock.tick(120)
  move_bullets()
  draw_everything()
  for event in pygame.event.get():
    if event.type == pygame.QUIT:
      running = False
    elif event.type == pygame.KEYDOWN:
      if event.key == pygame.K_ESCAPE:
        running = False
      if event.key == pygame.K_LEFT:
        my_dudes_x_position -= 15
      if event.key == pygame.K_RIGHT:
        my_dudes_x_position += 15
      if event.key == pygame.K_SPACE:
        bullets.append([my_dudes_x_position, 380])

pygame.quit()