How We Scaled Minecraft to 100K Connected Players with 5K Rendering Onscreen at Any Given Time

Who we are?

Hi, I'm Mihail Makei, Senior Software Engineer in MetaGravity - We're building the Quark Network Engine which parallelises and distributes simulations across a networked cluster of server and client computers. This enables games and virtual worlds to be scaled to massive, previously unthinkable sizes, while still keeping operating costs low.

We not only create the tech powering those worlds, but also our own large-scale game in development (our upcoming medieval MMO - Edge Of Chaos (here is the trailer - the battles scale is insane!)). Quark is also powering our partners' projects such as Chronoforge, Xsolla Metasites, Star Atlas,  Maians, Earth 2 and others.

Today I want to show you something special - a Minecraft Java Edition mod running on the Quark Engine - pushing Minecraft to 5000+ visible players and unlimited number - even 1m+ is not the limit - of concurrent players in a single world.

What is Quark Multiplayer Engine?

Quark Multiplayer Engine is a networking engine designed to remove the bottlenecks of traditional multiplayer architecture as well as overcome the weaknesses of older grid-based approaches to scale multiplayer games:

• A distributed simulation model called Causal Partitioning: The simulation in the gameplay loop is able to dynamically scale across many computers, overcoming the bottleneck of traditional game servers which  limit a single game instance to the best effort of a single server.

• Remove constraints in multiplayer game design: Game designers can throw more AI, physics or players at the game and Quark can elastically expand the simulation or contract it to suit the load, all within a single seamless instance.

• Server-Only Simulation: Older grid-based methods have to use strict server-only simulation within a single data centre to minimise the impact on the distributed tickrate. Our localised sync model eliminates this hard requirement
• Hard CCU (Concurrent Connected Users) limits: since avoid the distributed global state issue, we can keep scaling a game simulation horizontally across more computers without any end in sight
• Heavy bandwith and sync costs: in addition to the improved causal partitioning model, we've done lots of work on very low level networking such as kernel bypass and L2 broadcast protocols to achieve a 10x-100x gain over network usage efficiency. 

Here is what makes it different:

• Causal Partitioning Explainer: Our approach parallelises and distributes a simulation (gameplay loop) so that only a subset of the simulation needs to mutually synchronise at each tick of the game. Previous projects have aimed to parallelise gameplay but they do this by breaking the world into a grid. This causes worst-case synchronisation overhead which our causal partitioning model avoids
• Client-side simulation: Why should the server do all the work? Because of the localising sync behaviour of causal partitioning, we use geographically-dispersed networks of nodes to carry out the simulation. We move many systems to the client machines while ensuring consistency and synchronisation
• Dynamic Clusters: Need more capacity? Our clusters can dynamically grow or shrink, allocating machines as needed. No more monolithic servers breaking under load!
• Ultra-low bandwith usage: Efficient protocols and network transport ensures thousands of visible players at just hundreds of KB/s

We are building Unity and Unreal Engine quick-launch plugins which are now available in Early Access mode - feel free to sign up at quarkmultiplayer.com website for them and for the newsletter not to miss the latest news!

Why did we try Minecraft?

With 200 mln monthly players, Minecraft is more than a game - it's a global platform for creativity, education and storytelling.

It is also not built with traditional game engine such as Unity, Godot or Unreal, but instead uses its own Java-based engine - making it a perfect test case to prove the flexibility of our technology.

Plus, imagine the possibilities:

• Civilization-scale "server"
• Massive player-driven factions, elections and economies
• Persistent open worlds with thousands of mini-games
• Sandbox survival MMO of Minecraft with everyone playing in one massive persistent world

We saw an opportunity to build something the Minecraft world has never seen before!

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What were the challenges?

This is not just a mod adding a character or an item. Here is what we had to overcome:

Rebuilding the Networking layer

Minecraft runs everything on the server - from locomotion and combat to chunk generation - even in single player. Client's role is limited to collecting the inputs (keyboard, mouse, gamepad) and propagating them to server and rendering the prepared information received from the server (chunks, other players, NPCs).

To integrate Quark Multiplayer, we rewrote the networking layer from scratch and moved simulations to the client. Everyone who joins the game is providing compute power to the world! No more server-side waterfall calculations. Quark handles efficient synchronisation of the game state, persistence, authority transfer, and soon it will even enforce anti-cheat in a distributed way!

Rendering engine

Minecraft's legacy rendering engine is far from modern so we've had to optimise the rendering paths to support thousands of visible units without melting the GPU.

Stress testing  at Scale

Finding 10k real player for testing? Pretty hard, we have much less in our company. We built our own high-efficiency bot framework to simulate thousands of players using cloud machines:

• Each bot uses a separate connection to Quark Multiplayer Engine
• They navigate real Minecraft terrain and follow physics
• The AI script running them can be improved for more realistic scenarios but as-is they still place the same server-load as a real human player  

Running these tests by spinning up the required bot machines can consume heavy cloud costs so we are sparing with tests, but they are an effective way to prove the tech in preparation for real players.

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What have we achieved so far?

Our latest prototype hits these milestones:

• 5000-6000 visible players (VCUs) in a single scene at 20-60 FPS
• 100000+ concurrent users (CCUs) in one world
• Bandwith usage in the hundreds of KB/s, even with thousands of units visible

And yes, it is still Minecraft supporting:

• Player movement
• PvP combat
• Digging, placing blocks
• Basic crafting

More features are on the way!

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What are we planning to do next?

Here is our roadmap to public release:

• Support for NPCs, weather, terrain growth and other native features
• World-level systems like in-game economies, voting, moderation, mini-games and other custom server-specific solutions
• A one-click launcher to spin up your own hyperscale Minecraft server
• Anti-cheat validation to counter client-side simulation risks
• Public playtests - you will be able to try it on your own PC!
• Full mod release under Minecraft's EULA (yes, it will be free!)

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Where to Find Us?

Want to follow the development or try it early?

• Visit quarkmultiplayer.com to stay in the loop
• Follow us on X (Twitter) and LinkedIn
• Stay tuned for announcements, devlogs, and open playtest invites!

Let's push the limits of multiplayer together!