SYS_ID: ER-PAIEngineering Report

Pairs Arcade

React · WebGL · RedisMini Arcade with Online Multiplayer

Executive Overview

Pairs Arcade is a technical showcase of real-time state synchronization, offline-first PWA architecture, and server-authoritative multiplayer game logic.

DECISION_LOG //

The Challenge:
Needed a mobile-first mini arcade that goes beyond solo play — real-time online multiplayer with room codes, leaderboards, and friend groups, all in a single PWA that works offline.

Engineering Approach

We built 8 games (4 solo + 4 versus) with a Convex real-time backend. Every online move is server-validated using shared game engines, so the board can't be cheated. Hidden-info games like Battleship use server-side fog-of-war — secrets are redacted before reaching the opponent.

System Architecture

A hybrid PWA leveraging Service Workers for offline solo play, and Convex WebSockets for sub-50ms multiplayer synchronization.

Game Engine

Shared pure-function state reducers running on both client (for optimistic updates) and server (for validation).

Real-time Sync

Convex handling room state, presence, and atomic mutations.

Offline Layer

Workbox Service Worker caching audio, assets, and the solo-play WASM bundle.

Engineering Challenges

State Desync

Preventing race conditions when two players mutate the game state simultaneously. Solved using deterministic state machines and Convex's ACID-compliant mutations.

Fog of War

Ensuring clients cannot inspect the WebSocket traffic to cheat in hidden-information games. Solved by writing server-side projection functions that strip opponent secrets before broadcasting.

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