pygame-core

pygame Core

Build the foundation of a pygame game in Python: the main loop, delta-time movement, drawing with Surface/Rect, input, and Sprite/Group management. Targets pygame-ce 2.5.7 (the actively maintained community fork; same import pygame).

When to use

• Use when starting a pygame game, fixing the loop, frame-rate-dependent speed, input handling, blitting, or sprite/group collision.
• Use when code does import pygame and the project depends on pygame-ce (or pygame).

When not to use: Python language questions unrelated to pygame. 3D rendering (pygame is 2D). For cross-engine save/load use save-systems; for rebindable input architecture see input-systems.

Core workflow

1. Install pygame-ce, not legacy pygame. pip install pygame-ce — it's the maintained fork and imports as pygame. Don't install both in one environment.
2. Init and open a window. pygame.init(), screen = pygame.display.set_mode((w, h)), clock = pygame.time.Clock().
3. Run one loop: events → update → draw → flip. Pump the event queue every frame (for event in pygame.event.get()), update state, redraw, then pygame.display.flip().
4. Make it frame-rate independent. Get dt = clock.tick(60) / 1000 (seconds) and scale all motion by dt. Keep positions as floats; blit at integer rects.
5. Handle input two ways: event-based (KEYDOWN/MOUSEBUTTONDOWN, for discrete actions) and polled (pygame.key.get_pressed(), for held movement).
6. Organise objects with Sprite + Group. Subclass pygame.sprite.Sprite with image/rect; group.update(dt) and group.draw(screen) handle the batch. Run it and watch the window before assuming it works.

Patterns

1. Minimal game loop (the skeleton)

import pygame

pygame.init()
screen = pygame.display.set_mode((800, 600))
pygame.display.set_caption("My Game")
clock = pygame.time.Clock()

running = True
while running:
    dt = clock.tick(60) / 1000          # cap at 60 FPS; dt = seconds since last frame
    for event in pygame.event.get():    # MUST drain the queue or the OS thinks it hung
        if event.type == pygame.QUIT:
            running = False

    # update game state here, scaled by dt ...

    screen.fill((18, 18, 28))           # clear each frame
    # draw everything here ...
    pygame.display.flip()               # present the frame

pygame.quit()