Game 07

Snake

Python pygame deque Game Loop Collision Detection Grid Movement
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pygame

This game runs as a desktop app

Snake uses pygame for a real-time graphics window with arrow key controls. Browsers can't run pygame — there's no way to port the experience without rewriting it in a different language. Run it locally to play the full version.

How to run it locally

01Install pygame: pip install pygame
02Download snake.py from the GitHub repo below
03Run it: python snake.py
04Use arrow keys to move — eat food, don't hit walls or yourself
snake.py — source code GitHub ↗
""" PROJECT 7: Snake ================= Concepts: pygame game loop, event handling, grid-based movement, deque (efficient queue), collision detection, rendering """ import pygame import random from collections import deque # Config CELL = 20 COLS = 30 ROWS = 25 WIDTH = COLS * CELL HEIGHT = ROWS * CELL FPS = 10 # Colors (R, G, B) BLACK = (10, 10, 10) GREEN = (80, 200, 80) DARK_GREEN = (40, 140, 40) RED = (220, 60, 60) WHITE = (240, 240, 240) UP = (0, -1) DOWN = (0, 1) LEFT = (-1, 0) RIGHT = (1, 0) def draw_cell(surface, col, row, color, shrink=2): rect = pygame.Rect(col * CELL + shrink, row * CELL + shrink, CELL - shrink * 2, CELL - shrink * 2) pygame.draw.rect(surface, color, rect, border_radius=4) def main(): pygame.init() screen = pygame.display.set_mode((WIDTH, HEIGHT)) clock = pygame.time.Clock() def new_game(): start = (COLS // 2, ROWS // 2) snake = deque([start, (start[0]-1, start[1]), (start[0]-2, start[1])]) direction = RIGHT food = spawn_food(snake) return snake, direction, food, 0 def spawn_food(snake): snake_set = set(snake) while True: pos = (random.randint(0, COLS-1), random.randint(0, ROWS-1)) if pos not in snake_set: return pos snake, direction, food, score = new_game() game_over = False pending_dir = direction while True: for event in pygame.event.get(): if event.type == pygame.QUIT: pygame.quit(); return if event.type == pygame.KEYDOWN: # prevent reversing into yourself if event.key == pygame.K_UP and direction != DOWN: pending_dir = UP elif event.key == pygame.K_DOWN and direction != UP: pending_dir = DOWN elif event.key == pygame.K_LEFT and direction != RIGHT: pending_dir = LEFT elif event.key == pygame.K_RIGHT and direction != LEFT: pending_dir = RIGHT if not game_over: direction = pending_dir head = snake[0] new_head = (head[0] + direction[0], head[1] + direction[1]) hit_wall = not (0 <= new_head[0] < COLS and 0 <= new_head[1] < ROWS) hit_self = new_head in set(snake) if hit_wall or hit_self: game_over = True else: snake.appendleft(new_head) if new_head == food: score += 1 food = spawn_food(snake) else: snake.pop() # remove tail — normal move screen.fill(BLACK) draw_cell(screen, food[0], food[1], RED, shrink=3) for i, (col, row) in enumerate(snake): draw_cell(screen, col, row, GREEN if i > 0 else DARK_GREEN) pygame.display.flip() clock.tick(FPS) if __name__ == "__main__": main()

Concepts practiced

pygamegame loop + events
dequeO(1) head/tail ops
Collisionwall + self check
Gridpixel ↔ cell mapping
Setsfast food spawn check
Closuresnew_game, spawn_food

Reflection

I built a classic Snake game using pygame, representing the snake's body as a collections.deque so I could efficiently add to the head and remove from the tail in O(1) time without shifting a full list. I learned how a pygame game loop works — polling events, updating state, and rendering every frame at a fixed FPS; and how grid-based movement maps pixel coordinates to cell positions. The bug that stumped me most was the snake occasionally reversing into itself when keys were pressed quickly: the fix was introducing a pending_dir variable that buffers the next direction and only applies it at the start of each tick, preventing a mid-frame direction reversal.