Lucky Scratch

Lucky Scratch is an Android game I designed and developed end-to-end as a solo developer. Beyond being a casual game, the project was an experiment in client-side 2D gaming for Android, scalable backend ranking, and user behavior at scale, reaching 200,000+ downloads on Google Play Store. This was my first and only app for Android.

Technical Focus

This project involved full ownership of the system, from rendering and input handling on Android to backend ranking logic and cloud deployment.

Android Client (Native, Java)

• Custom 2D Rendering Engine Implemented directly on Android Canvas with bitmap blending to simulate realistic scratch interactions while keeping rendering lightweight and deterministic.
• Scratch Detection Algorithm Designed a point-cloud–based detection algorithm using Gaussian distributions to determine when a card was sufficiently scratched, tolerant to noisy or irregular user gestures.
• Game Loop & Logic Manual game loop management for consistent frame updates, animations, and input handling without relying on external engines.
• Card & Scoring Systems Multiple card types with distinct probability distributions, pricing, and reward logic, designed to be randomic rather than hardcoded.

Backend & Infrastructure

• Application Server (Java, Google App Engine) Implemented REST endpoints for score submission and leaderboard queries.
• Custom Leaderboard Ranking Algorithm Built an N-ary tree–based ranking system to efficiently insert and rank scores at scale.
• Lexicographic Score Ranking deterministic ordering for players with similar progress.
• Google Cloud Datastore (NoSQL) Used for scalable persistence of user scores and ranking data.
• Google Play Games Services Integration Authentication and user identity handled via Google Play Games, separated from game logic.