PZ-28 · Mini-Game — Falling Stars with Sound

Mini-Game — Falling Stars with Sound

Stars rain down from the top of the screen. Move your basket with arrow keys, catch them for points, and hear a chime each time you do. Miss one and a thud plays — and you lose a life. Today every skill you've learnt snaps together into one game.

⏱ 1 hour🎮 Game lesson📚 After PZ-27💻 VS Code or Thonny (desktop Python)

Learning Goals

3 min

By the end of this lesson you can:

Move a basket Actor with the keyboard and detect collision with a falling Actor.
Reset a star to the top of the screen after it is caught or missed.
Play a different sound effect for a catch versus a miss, and track score and lives.

Warm-Up · Collision Recap

5 min

You used colliderect in earlier lessons. Predict what this prints:

import pgzrun

basket = Rect((200, 350), (80, 20))
star_y = 360

if basket.collidepoint((240, star_y)):
    print("Caught!")
else:
    print("Missed!")

pgzrun.go()

Show the answer

Output

Caught!

The point (240, 360) is horizontally between 200 and 280, and vertically between 350 and 370 — so it is inside the basket.

New Concept · Respawning Actors

12 min

In a catching game, objects fall from the top, are caught or missed at the bottom, and then appear again. This is called respawning: resetting position and giving the object a new starting point.

Reset pattern

import random

def respawn_star(star):
    star.x = random.randint(20, WIDTH - 20)
    star.y = -20                    # start just above the screen

Placing the star at y = -20 means it begins just off-screen and glides smoothly into view. Randomising x keeps each fall unpredictable.

The catch-or-miss loop

def update():
    star.y += STAR_SPEED
    if star.y > HEIGHT + 20:        # star reached the bottom — missed
        respawn_star(star)
    elif basket.colliderect(star):  # star hit the basket — caught
        respawn_star(star)

Both branches call respawn_star — but only the catch branch awards points, and only the miss branch costs a life.

Worked Example · Falling Stars Catcher

12 min

Priya builds the full game. Save as star_catcher.py. You will need sounds/chime.wav and sounds/thud.wav in your project folder.

# star_catcher.py — part 1: setup and globals
import pgzrun
import random

WIDTH = 480
HEIGHT = 400
TITLE = "Star Catcher"

BASKET_SPEED = 5
STAR_SPEED = 3

score = 0
lives = 3

basket = Rect((200, 360), (80, 18))
star = Rect((0, 0), (20, 20))

def respawn_star():
    star.x = random.randint(20, WIDTH - 20)
    star.y = -20

respawn_star()

# star_catcher.py — part 2: update and draw
def update():
    global score, lives

    if keyboard.left and basket.left > 0:
        basket.x -= BASKET_SPEED
    if keyboard.right and basket.right < WIDTH:
        basket.x += BASKET_SPEED

    star.y += STAR_SPEED

    if star.y > HEIGHT + 20:
        lives -= 1
        sounds.thud.play()
        respawn_star()
    elif basket.colliderect(star):
        score += 10
        sounds.chime.play()
        respawn_star()

def draw():
    screen.fill("black")
    screen.draw.filled_rect(basket, "royalblue")
    screen.draw.filled_circle(star.center, 10, "gold")
    screen.draw.text(f"Score: {score}", topleft=(8, 8),
                     fontsize=22, color="white")
    screen.draw.text(f"Lives: {lives}", topleft=(8, 34),
                     fontsize=22, color="white")

pgzrun.go()

The global score, lives line is needed because update() writes to those variables. The basket is clamped inside the screen with the basket.left > 0 and basket.right < WIDTH guards.

A gold star falls from above; the blue basket waits near the bottom. Catching it plays a chime; missing it plays a thud.

Try It Yourself

13 min

01 🟢 Speed up over time

Make the game harder: increase STAR_SPEED by 0.5 every time the score reaches a multiple of 50. Add a line in update() after the catch branch.

Hint

global score, lives
# after score += 10 ...
if score % 50 == 0 and score > 0:
    global STAR_SPEED
    STAR_SPEED += 0.5

02 🟡 Two stars at once

Add a second star (star_b) with its own starting position. Both should fall independently. Use a second Rect and duplicate the catch/miss logic for it in update().

Hint

star_b = Rect((0, 0), (20, 20))

def respawn_b():
    star_b.x = random.randint(20, WIDTH - 20)
    star_b.y = -40         # stagger the start so they don't sync

respawn_b()

Mini-Challenge · Game Over Screen

8 min

When lives reaches zero, the game should freeze and display a large "Game Over!" message with the final score. Stars should stop falling. Combine today's game with a simple boolean flag you learned in Level 1.

It works if…

stars stop moving and "Game Over! Score: NN" appears when lives hit 0

Show one possible solution

game_over = False

def update():
    global score, lives, game_over
    if game_over:
        return                   # freeze everything
    # ... rest of update logic unchanged

def draw():
    screen.fill("black")
    if game_over:
        screen.draw.text("Game Over!", center=(WIDTH // 2, HEIGHT // 2 - 30),
                         fontsize=48, color="red")
        screen.draw.text(f"Final Score: {score}",
                         center=(WIDTH // 2, HEIGHT // 2 + 20),
                         fontsize=28, color="white")
        return
    # ... rest of draw logic unchanged

The return inside update() short-circuits all movement. The matching return inside draw() skips drawing the basket and star. One flag, two returns.

Recap

3 min

A catching game needs three things in update(): move the player, move the falling object, and check two outcomes — caught (sound + score) or missed (sound + life lost). In both cases, call respawn() to reset the object to a new random position above the screen.

Vocabulary Card

respawn: Reset a game object to a new starting position after it is caught or exits the screen.
global: Keyword that lets a function read and write a variable defined outside it.
colliderect: Returns True if two Rect objects overlap — used to detect a catch.
keyboard.left / keyboard.right: Boolean flags that are True while the matching arrow key is held down.

Homework

4 min

Add a high-score tracker to the catcher game. After game over, check whetherscore beats the current high_scorevariable. If it does, update it and display "New High Score!" in gold. If not, show the high score alongside the final score. Save as star_catcher_hs.py and bring a screenshot to the next class.

Sample · `star_catcher_hs.py`

# star_catcher_hs.py — high score extension
# (add this to the game-over branch of your draw() function)

high_score = 0

def update():
    global score, lives, game_over, high_score
    if game_over:
        return
    # ... movement and collision code from worked example ...
    if lives <= 0:
        game_over = True
        if score > high_score:
            high_score = score

def draw():
    screen.fill("black")
    if game_over:
        screen.draw.text("Game Over!", center=(WIDTH // 2, 140),
                         fontsize=48, color="red")
        screen.draw.text(f"Score: {score}",
                         center=(WIDTH // 2, 200), fontsize=28, color="white")
        if score >= high_score:
            screen.draw.text("New High Score!",
                             center=(WIDTH // 2, 240), fontsize=26, color="gold")
        else:
            screen.draw.text(f"High Score: {high_score}",
                             center=(WIDTH // 2, 240), fontsize=26, color="cyan")
        return
    # ... normal draw code ...

High score resets to 0 every run. PZ-32 will show you how to save it to a file so it persists between sessions.

Mini-Game — Falling Stars with Sound

⏱ 1 hour🎮 Game lesson📚 After PZ-27💻 VS Code or Thonny (desktop Python)

def update(): star.y += STAR_SPEED if star.y > HEIGHT + 20: # star reached the bottom — missed respawn_star(star) elif basket.colliderect(star): # star hit the basket — caught respawn_star(star)

# star_catcher.py — part 1: setup and globals import pgzrun import random WIDTH = 480 HEIGHT = 400 TITLE = "Star Catcher" BASKET_SPEED = 5 STAR_SPEED = 3 score = 0 lives = 3 basket = Rect((200, 360), (80, 18)) star = Rect((0, 0), (20, 20)) def respawn_star(): star.x = random.randint(20, WIDTH - 20) star.y = -20 respawn_star()

# star_catcher.py — part 2: update and draw def update(): global score, lives if keyboard.left and basket.left > 0: basket.x -= BASKET_SPEED if keyboard.right and basket.right < WIDTH: basket.x += BASKET_SPEED star.y += STAR_SPEED if star.y > HEIGHT + 20: lives -= 1 sounds.thud.play() respawn_star() elif basket.colliderect(star): score += 10 sounds.chime.play() respawn_star() def draw(): screen.fill("black") screen.draw.filled_rect(basket, "royalblue") screen.draw.filled_circle(star.center, 10, "gold") screen.draw.text(f"Score: {score}", topleft=(8, 8), fontsize=22, color="white") screen.draw.text(f"Lives: {lives}", topleft=(8, 34), fontsize=22, color="white") pgzrun.go()

game_over = False def update(): global score, lives, game_over if game_over: return # freeze everything # ... rest of update logic unchanged def draw(): screen.fill("black") if game_over: screen.draw.text("Game Over!", center=(WIDTH // 2, HEIGHT // 2 - 30), fontsize=48, color="red") screen.draw.text(f"Final Score: {score}", center=(WIDTH // 2, HEIGHT // 2 + 20), fontsize=28, color="white") return # ... rest of draw logic unchanged

Learning Goals

Warm-Up · Collision Recap

New Concept · Respawning Actors

Reset pattern

The catch-or-miss loop

Worked Example · Falling Stars Catcher

Try It Yourself

Mini-Challenge · Game Over Screen

Recap

Vocabulary Card

Homework

Sample · star_catcher_hs.py

Learning Goals

Warm-Up · Collision Recap

New Concept · Respawning Actors

Reset pattern

The catch-or-miss loop

Worked Example · Falling Stars Catcher

Try It Yourself

Mini-Challenge · Game Over Screen

Recap

Vocabulary Card

Homework

Sample · star_catcher_hs.py

Sample · `star_catcher_hs.py`

Sample · `star_catcher_hs.py`