Doodle Jump in Python- How to Code Doodle Jump

What You're Building

Doodle Jump is that annoying-addictive mobile game where a creature bounces upward on platforms forever. The core loop is dead simple: jump, land, bounce, fall, repeat. The "hard part" is making it feel responsive and actually fun.

You can build a working version in Python in under 200 lines. This guide gets you there.

What You Need Before Starting

Pygame is the standard choice for 2D Python games. It's not the fastest framework, but the API is straightforward and you won't waste time fighting with documentation.

Game Mechanics You Must Nail

Before touching code, understand the core systems:

Setting Up Your Project

Create a folder, install pygame, and make a main.py file. That's your entire project structure for now.

pip install pygame
mkdir doodle-jump
cd doodle-jump
touch main.py

The Core Code Structure

You'll need three main components:

The Player Class

The doodle needs position, velocity, and jump mechanics. Keep it simple:

class Player:
    def __init__(self, x, y):
        self.x = x
        self.y = y
        self.velocity_y = 0
        self.width = 50
        self.height = 60
        self.jump_power = -15
        self.gravity = 0.5
    
    def jump(self):
        self.velocity_y = self.jump_power
    
    def update(self):
        self.velocity_y += self.gravity
        self.y += self.velocity_y

The negative velocity makes the player move up. Gravity pulls it back down. This creates the bounce cycle.

The Platform Class

Platforms are rectangles with one job: exist at a y-position and wait for collision.

class Platform:
    def __init__(self, x, y, width=80, height=15):
        self.x = x
        self.y = y
        self.width = width
        self.height = height
    
    def draw(self, screen):
        pygame.draw.rect(screen, (0, 255, 0), 
                        (self.x, self.y, self.width, self.height))

The Game Loop

The game loop runs every frame. It handles input, updates positions, checks collisions, and redraws everything.

while running:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            running = False
    
    # Update player
    player.update()
    
    # Check platform collisions (only when falling)
    if player.velocity_y > 0:
        for platform in platforms:
            if player.rect.colliderect(platform.rect):
                player.jump()
    
    # Scroll screen when player goes above middle
    if player.y < SCREEN_HEIGHT // 2:
        player.y = SCREEN_HEIGHT // 2
        for platform in platforms:
            platform.y += abs(player.velocity_y)
    
    # Generate new platforms
    # Remove platforms that fell below screen
    
    pygame.display.update()
    clock.tick(60)

Making Platforms Appear Correctly

The tricky part is platform generation. You need random x-positions that are reachable from the previous platform.

def generate_platform(start_y, count=10):
    platforms = []
    for i in range(count):
        x = random.randint(0, SCREEN_WIDTH - 80)
        y = start_y - (i * 70)  # 70 pixels apart - always jumpable
        platforms.append(Platform(x, y))
    return platforms

The 70-pixel gap assumes your jump height covers about 200 pixels. Adjust based on your jump power and gravity values.

Handling Player Movement

Left and right movement uses keyboard input. Wrap around screen edges so the player can exit left and appear on right:

keys = pygame.key.get_pressed()
if keys[pygame.K_LEFT]:
    player.x -= 5
if keys[pygame.K_RIGHT]:
    player.x += 5

# Screen wrap
if player.x > SCREEN_WIDTH:
    player.x = 0
if player.x < 0:
    player.x = SCREEN_WIDTH

Collision Detection That Works

Only trigger a jump when the player is falling and lands on top of a platform. Checking velocity_y > 0 prevents double-jumps and landing on platforms from below.

if player.velocity_y > 0:
    player_rect = pygame.Rect(player.x, player.y, 
                              player.width, player.height)
    platform_rect = pygame.Rect(platform.x, platform.y,
                                platform.width, platform.height)
    
    if player_rect.colliderect(platform_rect):
        if player.y + player.height - player.velocity_y <= platform.y:
            player.jump()

The second condition ensures the player actually hit the platform's top surface, not its side.

Scoring System

Track the highest point the player reached. Display it in the corner:

score = max(score, int((start_y - player.y) / 10))
font = pygame.font.Font(None, 36)
score_text = font.render(f"Score: {score}", True, (255, 255, 255))
screen.blit(score_text, (10, 10))

Higher platforms = higher score. Simple.

Game Over Conditions

The player dies when they fall below the visible screen. Track this:

if player.y > SCREEN_HEIGHT:
    game_over = True

Show a game over screen with final score and restart option. That's it.

Library Comparison

Library Pros Cons Best For
Pygame Easy API, huge community, good docs Single-threaded, basic graphics Learning, prototypes
Pyglet Faster rendering, modern OpenGL Smaller community, steeper learning curve Performance-focused games
Arcade Object-oriented, built-in physics Less flexible, newer library Quick 2D games
Kivy Touch support, cross-platform mobile Complex setup, heavy framework Mobile-first projects

Stick with Pygame for this project. It's the path of least resistance.

Adding Power-Ups (Optional)

Once the basic game works, add variety:

Each power-up needs a collision check and a state modifier on the player object.

Common Problems

Getting Started Checklist

Work through this list. Get one thing working before moving to the next. The full game takes shape fast once the core loop functions.

Next Steps

Add sprite images instead of rectangles. Create a menu screen. Implement high score persistence with a text file. These are incremental improvements on a working foundation.

The code exists. The mechanics are understood. Ship it.