The latest articles on DEV Community by Domingos Martins (@domingos211). https://dev.to/domingos211 https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F4221237%2F55c2fe3e-2573-4915-8dd1-a43e7d272650.jpg https://dev.to/domingos211 en Domingos Martins Sun, 01 Nov 2026 22:05:08 +0000 https://dev.to/domingos211/running-classic-mu-online-season-6-in-the-browser-and-on-mobile-ee3 https://dev.to/domingos211/running-classic-mu-online-season-6-in-the-browser-and-on-mobile-ee3 <p>If you played MU Online back around 2005, you probably remember the setup: downloading a patchy archive, running <code>main.exe</code>, and praying legacy DirectX drivers wouldn't crash.</p> <p>We wanted to see how far we could take Season 6 using modern web standards, letting people play directly in a browser on both desktop and mobile without downloading a client. The result is <a href="https://openmu.com.br/en" rel="noopener noreferrer">OpenMU</a>.</p> <p><a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Farticles%2Ffj554y1sha5ds284bkjy.png" class="article-body-image-wrapper"><img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Farticles%2Ffj554y1sha5ds284bkjy.png" alt="What OpenMU offers" width="800" height="487"></a></p> <h2> The foundation: open source work </h2> <p>We didn't build this from scratch. This project stands on the shoulders of existing community efforts:</p> <ul> <li> <strong>Server:</strong> <a href="https://github.com/MUnique/OpenMU" rel="noopener noreferrer">MUnique/OpenMU</a>, an open-source C# (.NET) reimplementation of the classic Season 6 game rules and network stack.</li> <li> <strong>Client:</strong> built on <a href="https://github.com/Ignies/OpenMu-Client-Babylon" rel="noopener noreferrer">Ignies/OpenMu-Client-Babylon</a> (which evolved from afrokick's original JSClient), written in TypeScript and rendered with Babylon.js (WebGL).</li> </ul> <h2> Engineering compromises &amp; tweaks </h2> <p>Porting a 2000s desktop MMORPG into a browser comes with very specific bottlenecks:</p> <ul> <li> <strong>The network bridge (WebSocket to TCP):</strong> the original client protocol uses raw TCP sockets with SimpleModulus and XOR encryption. Browsers cannot open raw TCP sockets, so we run a lightweight proxy written in Bun that forwards bytes between WebSocket (WSS) and backend TCP. It maintains a 45-second keepalive and connection-level logging.</li> <li> <strong>Asset loading &amp; caching:</strong> assets are bundled into packages, served gzipped (reducing payload sizes to roughly a third), and cached locally via a Service Worker. The first launch takes around a minute while assets cache; subsequent visits load almost entirely offline.</li> <li> <strong>Rendering limits:</strong> dynamic shadows are only rendered for the 12 closest characters, and full equipment glow effects are limited to the 6 closest players. If the client drops below 22 FPS, it automatically toggles a stripped-down lightweight mode.</li> <li> <strong>Mobile input:</strong> classic MU relies on mouse clicks and keyboard potion shortcuts (Q/W/E/R). For mobile browsers, we integrated virtual joysticks, an auto-attack toggle, and support for the built-in MU Helper system.</li> </ul> <p><a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Farticles%2Fyvjn8jk9bm9u7eabonjr.png" class="article-body-image-wrapper"><img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Farticles%2Fyvjn8jk9bm9u7eabonjr.png" alt="Real gameplay on desktop and mobile" width="800" height="958"></a></p> <h2> The setup today </h2> <p>The server runs on standard Season 6 Episode 3 rules with a 20x EXP rate.</p> <ul> <li>The same account works interchangeably across desktop and mobile browsers (one active session at a time).</li> <li>We do not sell gear for real money, except for rentable pets. An optional VIP system offers an EXP bonus and access to <code>/offlevel</code>.</li> <li>All new accounts receive 5 days of VIP to test out the features.</li> </ul> <p><a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Farticles%2Fxm1pvwdjddq0kntowz0n.png" class="article-body-image-wrapper"><img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.us-east-2.amazonaws.com%2Fuploads%2Farticles%2Fxm1pvwdjddq0kntowz0n.png" alt="The in-game player market" width="800" height="420"></a></p> <p>We push updates weekly to improve rendering stability and touch controls.</p> <p>You can try it out here: <a href="https://openmu.com.br/en" rel="noopener noreferrer">https://openmu.com.br/en</a></p> <p>Feedback on performance, touch responsiveness, or browser quirks is very welcome!</p> showdev webdev gamedev javascript