Google Play In-App Purchases in Python/Pygame (Android)

A real-world implementation by Wonder Kofi Junior (AlmightyPrime)

From the game: Skiptrace — https://play.google.com/store/apps/details?id=com.almightyprime.skiptrace

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What this package contains

This is the complete, working implementation of Google Play In-App Purchases (IAP) inside a Python/Pygame Android game. Every file here is extracted from Skiptrace — a real game live on the Google Play Store. This is not a proof of concept. It runs in production.

skiptrace_iap_tutorial/
│
├── python/
│   └── iap.py                   ← The Python IAP wrapper (copy into your project)
│
├── java/
│   └── BillingShim.java         ← Custom Java billing wrapper (compile into your APK)
│
├── buildozer/
│   └── buildozer.spec           ← Buildozer config with [IAP RELEVANT] markers
│
└── example_usage/
    └── example_usage.py         ← Full game loop integration pattern

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Why a Java shim is needed

The Google Play Billing Library uses complex asynchronous Java callbacks that Pyjnius (the Python-Java bridge) cannot reliably implement in Python. Billing events fire on background threads at unpredictable times, which causes crashes or silent failures when handled directly in Python.

The fix: wrap all billing logic in a Java class (BillingShim.java) that pushes results into a thread-safe event queue. Python polls the queue each game frame using poll_purchase() — simple, safe, and crash-free.

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Quick start (4 steps)

1. Copy the Python file

Place iap.py in your project root (same folder as main.py).

2. Add the Java shim

Place BillingShim.java in:

your_project/src/main/java/com/yourpackage/yourapp/BillingShim.java

Update the package line at the top to match your own package name.

Then in buildozer.spec:

android.add_src = src/main/java

3. Add the Gradle dependency and permission

In buildozer.spec:

android.permissions = INTERNET, ACCESS_NETWORK_STATE, ACCESS_WIFI_STATE, com.android.vending.BILLING
android.gradle_dependencies = com.android.billingclient:billing:8.0.0, androidx.fragment:fragment:1.8.9
android.enable_multidex = True

4. Set up your products in Google Play Console

• Go to Play Console → Your App → Monetize → Products → In-app products
• Create a product for each item (e.g. "fruitpack1")
• The product ID must exactly match what you pass to iap.buy()
• Products only work on signed APKs uploaded to a testing track

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Using it in your game

import iap

# At startup (once)
iap.init_iap()

# When player clicks "Buy"
iap.buy("your_product_id")

# Every frame in your game loop
result = iap.poll_purchase()
if result:
    if result.startswith("purchased:"):
        product_id = result.split(":")[1]
        # Give the player their reward
    elif result == "failed":
        # Purchase cancelled or failed
    elif result == "ready":
        pass  # Billing connected — swallow silently

See example_usage/example_usage.py for the full pattern including cooldown guards, every event type handled, and the UI feedback message system from Skiptrace.

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Important notes

• IAP only works on a signed APK/AAB uploaded to Google Play's testing track
• It will NOT work on a debug build run directly via buildozer android debug
• Make sure com.android.vending.BILLING is in your permissions or purchases will silently fail
• The BillingShim uses consumeAsync() for consumable items (things the player can buy multiple times). For non-consumable items (e.g. "remove ads"), you would use acknowledgePurchase() instead — see comments in BillingShim.java

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Also available: Unity Rewarded Ads

If you need Unity Rewarded Ads for your Pygame Android game, a separate tutorial package is available covering unity_ads_android.py, ShowListenerShim.java, and full integration — also extracted from Skiptrace.

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About this implementation

Built by Wonder Kofi Junior (AlmightyPrime), a solo developer from Ghana. Two years of learning, failing, and finishing — on midnight internet data.

Support The Project

If this repository helped you integrate In App Purchase into your Pygame Android game, or if you'd like to try a fully integrated production example on Google Play, please consider:

Starring this repository Sharing it with other developers Downloading and rating Skiptrace on Google Play

Play Store: https://play.google.com/store/apps/details?id=com.almightyprime.skiptrace

Developer story: https://www.fixgamingchannel.com/from-a-jackie-chan-movie-to-google-play-the-story-of-skiptrace/

Your support helps me continue creating tutorials and open-source resources for the Pygame Android community.