5.1 Pygame setup and the game loop

We’re moving from text-based programs to a game window. Pygame is a library that gives you a window, shapes, colours, and keyboard input — everything you need for a simple game.

Install Pygame

In the terminal (or your IDE’s terminal):

pip install pygame

If you use Python 3 specifically: pip3 install pygame.

A minimal Pygame program

import pygame

pygame.init()
screen = pygame.display.set_mode((400, 300))
pygame.display.set_caption("My Game")

running = True
while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False

    screen.fill((0, 0, 0))   # black background
    pygame.display.flip()     # show the new frame

pygame.quit()

• pygame.init() — start Pygame.
• set_mode((width, height)) — open a window.
• Game loop — the while running: loop runs until the user closes the window.
• pygame.event.get() — list of things that happened (key press, mouse click, quit).
• pygame.QUIT — user clicked the close button.
• screen.fill((r, g, b)) — paint the whole screen one colour. (0, 0, 0) is black.
• pygame.display.flip() — make the new frame visible.

Important idea: you can’t “remove” shapes

In Pygame you don’t delete things from the screen. You redraw the whole frame every time. So each loop we:

1. Clear the screen (e.g. screen.fill(...)).
2. Draw everything that should be visible (player, obstacles, etc.).
3. Call pygame.display.flip().

Anything you drew last time is gone after the fill; only what you draw this time appears.

Project: Empty game window

1. Create a new file and run the minimal program above.
2. Change the window size and the background colour (try (30, 60, 100) for a blue).
3. Close the window with the X and confirm the program exits cleanly.

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Next: 5.2 Coordinates and drawing — the coordinate system and drawing rectangles.