Posted on 11th Dec 2025
| 3 Minute Read
Multiplayer has arrived at the Build 42 Unstable branch. It is a work in progress meant for stress testing, but it is here, and it already changes the rhythm of Knox Country. If you have been holding out for co-op in B42, now is the time to spin up a fresh world and get stuck in.
The Indie Stone advises playing on whitelisted servers or Steam co-op for the best results. Keep populations modest; under twenty players is the current guidance. Disable all mods for now, even client-side ones. Ragdolls are off in multiplayer and will return in later patches. Future Unstable updates may wipe saves, make sure you prepare yourself for potential restarts!
Saves from before 42.13 are not compatible. If you try to convert an older save, you risk losing items, animals and attributes. We recommend backing up first if you want to try this, that way you can always load it on an older version.
Build 42 itself remains a hefty step-up compared to the last update, you get deeper long-term crafting and industry chains, more reasons to farm and process. There are reworked interiors with basements and small layout changes that make house-to-house sweeps feel fresh. Professions and balance have been tuned so that specialisation matters.
With multiplayer in the mix, that long game turns into proper teamwork. Base builders raise walls while foragers and farmers keep the kitchen running. A mechanic keeps the fleet alive. Night runners take risks for rare loot. When everyone pulls in the same direction, progress snowballs.
Quality of life has moved on as well. Firearm target selection feels cleaner. Interior lighting is better; curtains and most barricades let little light through even when they block vision. Inventory handling is less fussy with extra actions while walking and more sensible double-clicks. The right-click menu is being tidied with new icons, and building plus crafting interactions keep getting polish.
If you want the easy route, host it with us. Our Project Zomboid server hosting gives you one-click updates, automated daily backups, full control of command lines and config, and regions close to your group. It is built for exactly this kind of rolling test where patches land often.
We have a short Knowledgebase guide that covers installing the Unstable branch both on your PZ server and on your PC via Steam. You can check that out here: Project Zomboid B42 Unstable multiplayer setup.
