Dedicated Simulation

Sarkastic.gg Dedicated Simulation

Source code · Report a bug · Changelog · Resource Regrowth

Fork of Serverside Simulations by ddormer, which is no longer maintained as of 2026, renamed at the original authors' request. Updated for Valheim 1.0, building on ddormer/valheim-serverside#118 by @mreastman.

The dedicated server simulates the world — monsters, physics, ships without a driver — instead of handing each area to whichever player got there first. Server-side only: players keep vanilla clients.

Companion plugin: Resource Regrowth () brings back surtling cores, chest loot, creatures and whole zones in areas left alone; the two are made to run together.

Updated for Valheim 1.0.16. Up to version 1.12 it was also checked on 1.0.15 and 1.0.12; what was added after that is tested on 1.0.16 only. A startup check warns about every vanilla method the mod uses that a game update has changed.

Why, compared to vanilla

In vanilla, the first player to enter an area owns it: their game runs the monster AI and physics there, and everyone else nearby sees that area through them. If that player has a poor connection or a slow PC, everyone around suffers — monsters jump around, hits land late — and updates travel from each player to the server, on to the owner and back.

With this mod the server owns and simulates those areas:

• Each player depends only on their own connection to the server, not on someone else's.
• Clients no longer run AI and physics for the areas they would have owned, which helps slower PCs.
• Ships are handed to their driver, so steering has no round trip.

What it costs:

• The server needs more CPU, RAM and upload than a vanilla server.
• A player alone in an area now has their round trip to the server where vanilla would have had none. With a nearby server this is rarely noticeable.

Observed on one server

Valheim 1.0.7, Windows dedicated server, up to four players, September 2026. One group's session, not a benchmark.

• No exceptions or mod warnings during play.
• Items picked up from the ground: 98% of 437 on the first ownership request (1.2.0), 214 of 214 (1.5.0); the rest within 2 s.
• The per-player send queue was full in at most 0.2% of send ticks, only in bursts such as portals.
• About 0.8 of a CPU core on average with one player, and 15–25% of a core while empty (with the job worker cap). RAM about 1.6 GB empty, 2–2.6 GB with players, levelling off.

Not covered yet: Frost Foundry, sailing, raids, Deep North events, a non-default -simulationdistance, and the console commands under a Windows server panel.

What this fork adds

Compared to Serverside Simulations 1.1.9 (details in the changelog):

• Valheim 1.0 support, and a review of every patched method against the 1.0 code.
• Fixes: location prefabs were never released (a memory leak); zones could be generated before their locations; no objects were created with a non-classic -simulationdistance; 1.0 errors on the server with ship sails, the Frost Foundry (which duplicated items) and leviathans; the far ring of unexplored land was not pre-generated as in vanilla, so distant trees, cliffs and the Mistlands mist appeared late.
• Objects nearest to a player are created first, e.g. after a portal.
• Server-side networking limits from BetterNetworking, with a per-player log of how often they are reached.
• Cap on Unity job worker threads, which otherwise idle at CPU cost on many-core hosts.
• Fix: player changes that the save skipped. Valheim 1.0 rewrites only the world chunks it marked as changed, and a change received from a player marks nothing, so what a player just built or moved could be missing after a restart.
• Fix: teleported players left behind as ghosts. A player who portalled or respawned stayed visible to the players near the old spot, frozen, until they next crossed a zone line, because Valheim 1.0 checks whether an object left their area before it stores the new position.
• Fix: fireplaces smothered for everyone but the server.