Valheim world modifiers, presets and moving worlds

Valheim's difficulty is not a single slider. It is five modifiers, four switches and seven presets, all set as launch arguments on a dedicated server because the server has no configuration file. They are applied at start, they stick to the world, and they can be changed later without touching a single build or losing any progress - which makes them the most reversible decision you will make about a server, and the one groups argue about the longest. This post takes each value apart, explains which ones change how the game is played rather than just how hard it is, and then covers the other half of the job: getting a specific seed onto a dedicated server, moving a world in from someone's PC, and getting it back when a save goes wrong. The server itself - ports, passwords, admin lists - is in the Valheim dedicated server guide.

How modifiers reach the server#

Three arguments, and they stack in a defined order:

$ ./valheim_server.x86_64 -nographics -batchmode \    -name "Crew" -world "Midgard" -password "herring-barrel-42" \    -preset casual \    -modifier combat hard -modifier portals casual \    -setkey nobuildcost -setkey nomap

-preset is applied first and sets all five modifiers at once. Each -modifier then overrides one of them, so the line above is "casual, except combat is hard and portals allow everything". -setkey turns on a switch that no preset except a couple touches. Both -modifier and -setkey can appear as many times as you need.

Each -modifier takes two separate tokens, the name and the value, not one quoted string. -modifier combat hard is correct; -modifier "combat hard" is silently ignored, and so is -modifier combat veryHard with the wrong capitalisation. That silence is the running theme: Valheim does not reject a bad modifier, it just does not apply it, and the first you hear about it is a player wondering why the greydwarves still hit so hard.

On a panel host you will not write that command line. The same arguments are fields on the Startup tab, usually one for the preset and one free-text field for extra arguments, and the two-token rule still applies inside that field. In single player the same settings live behind a world modifiers screen in the pause menu; clients connected to a dedicated server do not get that screen, because the server owns the rules.

The presets, and what each one is for#

immersive and hammer are the two that are not really difficulty settings. immersive removes the map and the portal network, which turns Valheim into a game about landmarks and longships; it is excellent and it is not for everyone, and it is close to impossible to walk back once a group has built around it. hammer removes build costs entirely, which is what you want for a creative build server and nothing else - it makes the progression meaningless, so run it on a second world rather than your main one.

A preset is a starting point, not a mode. Nothing about the server behaves differently once a preset is applied; it has simply set the five modifiers, and you are free to override any of them. There is no way to see "which preset is active" later, because after the first start there is no preset, only the five values it set.

Every modifier and its values#

`combat` scales the damage in both directions. It does not change enemy behaviour, spawn rates or the biome progression, so veryeasy still means a plains trip at the wrong time kills you - it just takes a little longer. Worth knowing before you set it: Valheim already scales enemy health and numbers with how many players are in an area. A group of eight on combat normal is fighting a harder game than a duo on combat hard, which is why large groups often end up lowering it rather than raising it.

`deathpenalty` is the one that changes how people play. At casual you keep your items and your skill progress, so death costs you the walk back. At hardcore there is no tombstone at all and what you were carrying is gone. The values in between trade off how much skill progress you lose against whether you can recover your gear. The in-game world modifier screen prints the exact effect of each option in one sentence, and that text is the authority - it has been reworded between updates, and a wiki page is more likely to be stale than the game is.

`resources` multiplies what you get from mining, chopping, pickables and creature drops. It is the safest dial to move for a group with limited evenings: more roughly halves the grind without touching any of the game's threats. Going to most breaks the pacing, because Valheim's progression gates are built on how long it takes to accumulate metal, and removing that leaves a very short game.

`raids` controls the frequency of the base attack events. none switches them off completely, which is the right answer for a builder-focused server and the wrong answer for almost everyone else - the raids are most of the reason defences exist. less is the setting for a group that keeps losing workbenches while nobody is online.

`portals` is the single most consequential modifier in the game. Valheim is designed around metals not fitting through portals, which is what makes boats, cart routes and outposts matter. casual lets everything through and removes that entire layer. Some groups love it and some groups find the game hollow afterwards. Decide before the first swamp trip, not after, because reversing it turns a solved logistics problem back into an unsolved one. At the other end, veryhard removes portals altogether, which is the immersive preset's defining feature.

The setkey switches#

-setkey takes one name and turns that switch on. Four are part of the modifier system:

playerevents is the underrated one. By default, raid events are chosen by what the world has achieved, so a friend who joins a mature server in bronze gear gets plains-tier events at their new base. With playerevents on, each player gets events matched to their own progress, which is what makes a long-running server joinable by newcomers. If your server outlives its first group, turn it on.

nomap does more than remove a convenience. Without the map there are no pins, no shared markers and no way to describe a location except by landmark, which changes how a group plays together far more than a combat setting does. Try it on a new world before applying it to one people have already mapped.

passivemobs exists for building and screenshot servers. It is not a difficulty setting so much as a different game.

Changing the rules on a world that already exists#

You can, and nothing is lost. Modifiers are rules applied as the world runs, not properties baked into the terrain. Stop the server, change the arguments, start it again; every build, chest, character and explored chunk is exactly where it was.

Two practical cautions.

First, set values explicitly rather than deleting an argument. Modifier state is stored with the world, and whether removing -modifier combat hard returns combat to normal or leaves the last value in place is not something to find out by assumption. Write -modifier combat normal and you know what you have.

Second, a rule change only applies going forward. Turning deathpenalty down does not give anyone back the skills they lost last week. Turning raids to none does not cancel an event that has already started. And resources more does not retroactively fill the chests.

The safe sequence for a change on a live server is the same one you would use for any configuration change: stop cleanly so the world saves, take a backup, change one thing, start, and confirm the effect in game before changing the next. Valheim saves on a timer rather than continuously, so stopping cleanly is not a formality - a killed process discards everything since the last save.

Seeds: the one thing you cannot set at launch#

There is no seed argument. The dedicated server cannot be told to generate a world from a seed; it either loads the world files it finds or generates a random one. If you want a specific seed - a well-known one, or a map somebody scouted - the route is:

1. Create the world in single player, typing the seed into the world creation screen.
2. Quit to the main menu so the files are written.
3. Upload the two files to the server.
4. Start the server with -world set to that name.

The seed lives in the .fwl file, which is a few hundred bytes of metadata. That is why uploading only the .db produces a world that looks wrong: the terrain is regenerated from whatever seed the server has, and the stored objects no longer line up with it. The two files are a pair and always move together.

To read the seed of an existing world, open the game's world list and select it; the seed is shown on the selection panel. There is no way to change the seed of a world that exists, because the terrain is generated from it on demand rather than stored.

Moving a world in, and getting one back#

A Valheim world is two files. Characters are a third, and they live on each player's own machine.

worlds_local/    Midgard.fwl                              seed and metadata    Midgard.db                               everything else    Midgard.fwl.old                          the previous save    Midgard.db.old    Midgard_backup_auto-20260921-031500.db   automatic backupcharacters_local/    Odin.fch                                 a character, on the player's PC

Where to find them on a client machine:

If the Windows folder is empty, the world is in Steam Cloud instead. Open the game, use Manage Saves, and move it from cloud to local before you go looking for the file again.

The upload itself:

1. Stop the server. Uploading over a running world achieves nothing, because the next save writes memory over your file.
2. Upload both files to worlds_local, over SFTP or the file manager - SFTP and the file manager has the connection details.
3. Match the name exactly, capitals included. -world "Midgard" loads Midgard.db, and midgard.db on a Linux server is a different file.
4. Start and watch the log for the world being loaded rather than created. If it says it generated a world, the name did not match and your original files are untouched beside the new ones.

Recovery works the same way in reverse. The .old pair is the previous save; the timestamped files are the automatic backups controlled by -backups, -backupshort and -backuplong. To roll back, stop the server, move the live pair aside, rename a matching .db and .fwl pair into place, and start. Always take both halves from the same point in time.

Those built-in backups live in the same folder on the same disk as the world, which means they protect you from a corrupt save and from nothing else. Real backups go somewhere the server cannot reach, on a schedule, and get restored occasionally to prove they work - backups that actually restore and testing a restore before you need it are the argument. On RE:NODE backup slots are on every Valheim plan, they are stored off the machine they protect, and restoring is a button; the Schedules tab will take the nightly one on a cron expression. Moving between plans changes the limits on the server you already have, so the world stays where it is, which is a different job from moving a server without losing players.

Troubleshooting#

A modifier had no effect. Check the spelling of the value, check it is two tokens rather than one quoted string, and check a preset later on the command line is not resetting it. Order matters: put -preset first.

The world regenerated with a new map. The -world name does not match the files, or only the .db was uploaded. Your originals are still in worlds_local. Fix the name, delete the world the server just made, restart.

The seed is not the one I chose. The .fwl did not come across, or it came from a different world than the .db. Re-upload the pair together from the same source folder.

Players still get raids after `-modifier raids none`. An event already in progress runs to completion, and none does not stop scripted encounters that are part of the world rather than the raid system. Give it a restart and a day before concluding it failed.

Difficulty feels wrong for the group size. Enemy scaling with nearby player count is doing the work, not your modifier. Eight players in one place is the hardest Valheim gets at any combat setting.

The world reverted to yesterday. A restore happened, or the server started from a .old file after the live pair was damaged. Check the file timestamps in worlds_local before doing anything else, and copy the whole folder somewhere safe before experimenting.

FAQ#

Can I change difficulty without starting a new world?

Yes. Modifiers are applied at start and affect the rules from then on. Stop the server, change the arguments, start it: builds, chests, characters and explored map are all untouched.

Do world modifiers work on a server with mods?

Yes, and they are applied by the game rather than by BepInEx, so they are unaffected by a mod update. Where a mod also changes combat or resource values, the two stack in ways nobody has documented, so change one at a time. Installing mods on a server is covered in Valheim mods with BepInEx.

Can players see which modifiers are active?

Not as a list. They see the effects, and a world running non-standard settings is marked as modified in the game's own interface. If your group needs to know the rules, write them in the server description or a pinned message.

What is the difference between the immersive preset and -setkey nomap?

nomap removes the map only. immersive removes the map and sets portals to their most restrictive value, so it changes travel as well as navigation. You can build the same thing by hand with two arguments if you want the map gone but the portals kept.

Can I run two worlds on one server?

Not from one process. One Valheim server loads one world. Running a second world means a second server on a second pair of UDP ports, with -instanceid set differently so the two do not confuse each other's session registration.

Are the automatic backups enough?

No. They sit in the same folder as the world, on the same disk, and they protect against a corrupt save rather than a deleted server, a bad upload or a mistake made with the file manager. Keep a copy somewhere the server cannot write to.