Integrating Large-Scale Multiplayer in Unreal 4.26

ChronoForge, an action MMO built on Unreal Engine 4.26, aimed to evolve from small, instanced dungeon raids into a dynamic, shared overworld experience. However, Unreal’s native networking and legacy performance constraints made scaling beyond 2–5 player sessions nearly impossible. Through a rapid partnership, the MetaGravity Solutions team integrated the Quark Multiplayer Engine into their project —replacing the existing session-based architecture and enabling large-scale social gameplay while the core team continued to develop the gameplay. In parallel, they solved significant rendering and optimisation challenges, ultimately achieving smooth performance with over 200 concurrent players in a single space—all within the limitations of Unreal 4.26.

ChronoForge is an ambitious multiplayer action adventure with a large number of character classes each with unique abilities, that set out to deliver a hybrid multiplayer experience: small team-based dungeon instances where players acquire game currency and rare items, combined with a persistent “overworld” open world. Built in Unreal Engine 4.26, the game was originally designed around 2–5 player co-op missions. As the vision expanded, the developers wanted to support real-time player interaction at a much larger scale—enabling hundreds of players to gather, trade, and prepare for missions in a shared overworld. The goal was to create a vibrant, socially driven MMO without moving to a newer engine or rearchitecting the game from scratch.

Unreal Engine 4.26’s default networking was designed for small sessions, not massive social hubs. ChronoForge’s initial implementation began to break down when player counts rose above a dozen. Network lag, state desync, and replication overhead made stable large-scale multiplayer unfeasible. After review of the existing code and assets, new problems emerged: the game’s rendering pipeline struggled to handle more than five characters on screen without a major performance hit due to the large number of character customisations, outfits and items possible. With UE4.26 lacking the modern optimisation tools introduced in UE5, the team had to find creative solutions within a technically limited environment.

MetaGravity led a two-pronged approach. First, they migrated ChronoForge’s networking stack from Unreal’s built-in session model to Quark Multiplayer. This rapid transition period was done within a month and enabled support for over 2,000 CCUs, organised into scalable architectures with 100-player overworld hubs and seamless transitions into instanced dungeons. This drastically reduced replication load and eliminated lag in social areas.

Second, they tackled rendering and performance. MetaGravity conducted a full audit of the game’s asset and visual pipeline, identifying key bottlenecks in materials, skeletal meshes, and draw calls. They implemented tailored optimisations including shader simplification, LOD tuning, and skeletal mesh refinement. Crucially, these changes were made within Unreal Engine 4.26—avoiding the risks and costs of a full engine upgrade.