Valheim world modifiers on your server

Valheim's world modifiers set the difficulty and pace of a world: how hard you hit and get hit, what dying costs you, how often raids turn up, what a portal will carry and whether the map exists at all. They're chosen once, when the world is created, and then they live inside that world's own save data for as long as the world exists.

Your Valheim server's Startup tab sets them for you. It's laid out like a config editor: a search box at the top, then one card each for Server, World, Difficulty, World toggles and Saves and backups. The World preset sits in the World card, the five dials in Difficulty and the four toggles in World toggles. Every option says what it does in numbers, for example Hard: enemies deal 150% damage, you deal 85%, and the line under each dial spells out the option you picked in full. Pick them before the world's first start, press Save changes on the card (or Save all in the bar that appears once you've changed more than one card), and start the server. If you'd rather build the world on your own PC in single player, that works too: upload the finished world to your server, and the modifiers come with it, since they're saved inside the world itself, not in a separate settings file.

The figures in this guide and in the Startup tab are the values the game itself stores in a world's save: we created a fresh world for every preset and every modifier level on a test server and read them back. Every dial left on Game default (Normal) plays as the Normal column below.

What a preset sets

Valheim ships seven presets. A preset changes only some modifiers and leaves the rest on Normal, and any dial you set in the Difficulty card overrides its part of the preset.

Hammer is built for creative building rather than survival. Immersive keeps Normal combat but turns off portals and the map, so you travel on foot and find your way by landmarks and memory. Fire hazard is a preset-only setting; it has no toggle of its own.

The individual modifiers, in numbers

Instead of, or on top of, a preset, five dials and four on/off toggles can each be set on their own.

Combat changes how hard you hit, how hard enemies hit back, how fast and big they are and how often they have stars. Each figure is a percentage of Normal.

Death penalty is what dying costs you: a share of every skill, and what happens to the gear you have equipped and to the rest of your inventory.

Dropped items wait in your tombstone where you died; destroyed items are gone. The game stores skill loss as a share of Normal's 5%: Casual and Very easy are 15% of it, Easy 50%, Hard 150%.

Resources multiplies what trees, rocks, ore and creatures drop.

Raids sets how often monsters raid your base. The game stores it as the wait between raid checks, as a share of Normal's.

Portals sets what a portal will do.

The launch flags, for completeness

On a dedicated server, Valheim reads three flags for this: -preset <name> (one of the presets above), -modifier <name> <value> (one of the five dials, repeated for more than one), and -setkey <name> (one of the four toggles, also repeatable), for example -modifier combat hard -modifier deathpenalty hardcore -setkey nobuildcost. You don't type these yourself: the World preset, Combat, Death penalty, Resources, Raids and Portals fields and the World toggles card in the Startup tab add them for you, and a field left on Game default (Normal) adds nothing, so the game decides. Uploading a world you built with the modifiers already set does the same job from the other direction: the modifiers are saved in that world's files.

Move a world with modifiers onto your server

1. Back up what's running now. Open your server's Backups tab and create a backup before you touch anything. How to create and restore backups covers restoring one if you need it.
2. Create the world locally. In Valheim on your PC, start a new game, click Modify next to the world you're creating, pick a preset or set individual modifiers, and give the world a short name using only letters, numbers, dashes and underscores. Our panel's World Name field only accepts up to 20 of those characters, so keep the name plain now rather than renaming files later.
3. Find the world. Press Win+R and paste %userprofile%\AppData\LocalLow\IronGate\Valheim\worlds_local. Current versions of Valheim save the world as a folder named YourWorld, holding _main files and .chunk files. Zip that folder, since the File Manager uploads files, not folders. An older save is a matching pair instead, YourWorld.db and YourWorld.fwl; use the pair only if there's no folder.
4. Stop your server from the dashboard before you upload anything. Valheim writes to its world files while it runs, and uploading into a live world folder risks a corrupted or half-written save.
5. Upload the world. In the File Manager, open .config/unity3d/IronGate/Valheim/worlds_local (it appears after the server's first boot; start it once if the folder isn't there yet). Upload the zip, click Extract here, then delete the zip, so you end up with worlds_local/YourWorld/ holding the _main files. For a pair, upload the .db and .fwl straight into worlds_local.
6. Set World Name. In the Startup tab, set World Name to the folder or file name exactly, without any ending.
7. Start the server and watch the Console for DungeonDB Start, which means your uploaded world loaded. Join and check the modifiers took, for example a hit that shouldn't down you on Casual, or no cost at the crafting bench with No Build Cost on.

Changing modifiers on a world you already have

Change the fields in the Startup tab, press Save changes on the card, and restart: the server is given them on every start. Valheim keeps modifiers inside the world's save, so join and check the change took on a world that already existed, the same way as step 7 above. Valheim itself can also change some modifiers live from its own admin console (press F5 in-game, then devcommands, then setworldmodifier or setworldpreset) if you're on the server's admin list, but that flags the save as having used console commands, which Iron Gate then excludes from earning further achievements. Treat that as a workaround, not something this guide recommends.

The clean way to change modifiers is the same route as above: create a fresh world locally with the settings you want and upload it under its own name. Your existing base doesn't come with it, only the world resets; your characters carry over fine, since Valheim keeps characters and worlds as separate files.

Common mistakes

• World Name doesn't match. Off by one character, or a name with a space, and the server quietly starts a fresh world instead of loading yours.
• Uploading while the server is running. Stop it first, every time.
• Uploading the old pair when there's a folder. If worlds_local on your PC has both a YourWorld folder and a YourWorld.db + YourWorld.fwl pair, the folder is the current save and the pair is an older copy. Upload the folder.
• Only uploading the .db. With an older pair, the .fwl carries the world's name tag; without it the server won't recognise the pair as a world it can load.
• Extracting into the wrong place. The _main files must sit in worlds_local/YourWorld/, not one folder deeper.
• A name that doesn't fit World Name's rules. Spaces, punctuation beyond dashes and underscores, or anything over 20 characters won't save in the Startup tab, so you're stuck renaming the local files anyway. Name the world plainly from the start.
• Crossplay with a modded, hand-tuned world. The modifiers themselves work fine with crossplay on. If you're also running mods, turn Crossplay off in the Startup tab first, since console players can't install mods and mods don't mix reliably with crossplay's networking, as Valheim server: join code, crossplay, mods explains.

Once your world is on the server with the modifiers you picked, How to install BepInEx and mods on your Valheim server covers adding mods on top, and our Valheim plans page has RAM sizing if a bigger crew or heavier modifiers need more headroom.