Building a Retro Game Platform with EmulatorJS & Next.js

delapise — Wed, 29 Apr 2026 08:10:30 +0000

🎮 Building a High-Performance Retro Game Platform with EmulatorJS

Hey everyone! 👋

I recently launched a retro gaming platform, playeretro.com, built entirely on top of EmulatorJS. I wanted to share my experience, some technical optimizations I've discovered, and how we managed to get smooth 60FPS gameplay for classics like The King of Fighters 97 directly in the browser.

Why EmulatorJS?

We chose EmulatorJS for several reasons:

Broad System Support: It handles NES, SNES, GBA, N64, and more with a unified interface.
WebAssembly Performance: The core is incredibly fast, even on lower-end devices.
Customization: The API allows for deep integration with modern web frameworks.

🚀 Technical Optimizations (Lessons Learned)

During the development of playeretro.com, we ran into a few bottlenecks. Here is what worked for us:

1. Lazy Loading Cores

Instead of loading all emulator cores at startup, we dynamically import the specific .wasm core only when a user selects a game. This reduced our initial bundle size by 60%.

2. Pre-caching BIOS & Assets

We used Service Workers to cache common BIOS files and game metadata. This ensures that returning users see a near-instant load time.

3. CDN for ROMs

Hosting ROMs on a high-speed CDN (we use Cloudflare) is critical. EmulatorJS streams the data efficiently, but latency is the enemy of emulation.

🛠️ Integration Example

Here is a simplified snippet of how we initialize the emulator:


javascript
const EJS_player = document.getElementById('game-screen');
const config = {
    "id": "game-screen",
    "system": "nes",
    "gameUrl": "/path/to/game.rom",
    "core": "fceumm",
    "background": "#000000"
};
// EmulatorJS auto-init or manual init depending on version

Forem: delapise