Building a "No-Lag" 2D Multiplayer Game (Clueland) with Next.js, Express, and WebSockets

Hey r/webdev / dev.to!

I've been working on Clueland, a persistent 2D economic life simulator that aims to bring a truly real-time, shared world experience to the browser. We're launching soon, and I wanted to share some of the technical journey and challenges, especially around making a large-scale map feel "lag-free."

The Core Problem: How do you render hundreds of player plots, mining rigs, and moving vehicles for thousands of players in real-time without crashing the browser or hitting server limits?

Our Solution Stack:

Frontend: Next.js + PixiJS (for GPU-accelerated canvas rendering)

Real-time: Socket.io (for instant state synchronization)

Backend: Express.js + PostgreSQL/Prisma (for persistent game state)

Scaling: Docker Compose + Nginx (for microservices and load balancing)

Key Challenges & Learnings:

Spatial Partitioning: We broke the world into chunks and only stream visible chunks to the client. This significantly reduced bandwidth and client-side rendering load.

State Synchronization: Implementing a robust diffing algorithm over WebSockets to only send state changes, not the entire world, preventing "lag spikes."

Canvas Performance: Optimizing PixiJS with texture atlases (for ground, trees, vehicles, etc.) to ensure 60 FPS even with thousands of sprites.

CORS & Docker in Prod: Navigating production Docker environments, Nginx proxying, and ensuring NEXT_PUBLIC_API_URL variables were correctly passed at build time (a recent headache!).

We're now in final testing, focusing on stress-testing the multiplayer map. I'd love to hear your thoughts on the architecture, any potential bottlenecks you foresee, or how you've tackled similar problems.

Link to Game: clueland.in

Thanks for reading!