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 Fork of Serverside Simulations by ddormer, which is no longer maintained as of 2026, renamed at the original authors' request.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 (Thunderstore) brings back surtling cores, chest loot, creatures and whole zones in areas left alone; the two are made to run together.

Updated for Valheim 1.0.20 (the game's own code this mod depends on is unchanged from 1.0.16; the Ward guard and the keep-clear rule of the Portal lock, added in 1.19, were tested on 1.0.20, the older features on 1.0.16 and they have run on 1.0.20 since). Up to version 1.12 it was also checked on 1.0.15 and 1.0.12. 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):