What world modifiers are
World modifiers arrived with patch 0.217.14, Hildir's Request, as a World Modifiers button on the start game screen with many customisation and difficulty options. You either pick a preset or design your own mix, with settings for combat, death penalty, portals, resources, raids and more.
At first they only applied to worlds started from the game. Patch 0.217.22 brought them to dedicated servers, in Iron Gate's words, using parameters in the startup file or using the console as an admin, and updated the dedicated server manual with the details. That manual is the guide on valheim.com, and it is the source for every option and value below.
Players see a server's choices before they join, since the server list shows a summary of each server's modifiers. That makes modifiers part of how you describe a server, not only how it plays.
The seven presets
Iron Gate's guide gives seven valid values for -preset: Normal, Casual, Easy, Hard, Hardcore, Immersive and Hammer. Its own example is written -preset hard.
The guide names the presets but does not list what each one sets. The simplest way to see that is in your own game: start creating a world, open World Modifiers, pick a preset and read the summary it shows. One detail is confirmed in Iron Gate's patch notes: the Ashlands update added a modifier that lets fire spread outside the Ashlands as well, as part of the Immersive preset.
A preset is a starting point, not a lock. You can take a preset and then adjust single modifiers after it, which is where the ordering rule comes in.
- -preset normal, casual, easy, hard, hardcore, immersive or hammer
- One preset per start line
- Immersive includes the fire spread modifier, according to the Ashlands patch notes
- Check the summary in your own game to see what a preset sets
The five modifiers and their levels
-modifier takes a modifier name and a level, as in Iron Gate's example -modifier raids none. There are five modifiers, each with its own list of levels. None of the lists includes a normal level, because leaving a modifier out keeps it at its default.
Iron Gate's guide is firm on one rule: if you combine a modifier with a preset, the modifier must come after the preset. A preset overwrites any modifier set before it, so -modifier raids none -preset hard gives you plain Hard with raids, while -preset hard -modifier raids none gives you Hard without them.
DeathPenalty is the one most groups argue about. Its levels run from casual to hardcore, and since a change here alters what players lose on death, agree on it before the first night rather than after the first lost inventory.
- Combat: veryeasy, easy, hard, veryhard
- DeathPenalty: casual, veryeasy, easy, hard, hardcore
- Resources: muchless, less, more, muchmore, most
- Raids: none, muchless, less, more, muchmore
- Portals: casual, hard, veryhard
The four keys
-setkey switches on a world modifier checkbox. Iron Gate's guide lists four valid keys, with -setkey nomap as its example. Each one is a separate -setkey on the start line.
nomap removes the map, and it has been a server setting since patch 0.207.20, which reworked no map mode. passivemobs is the passive mobs modifier, and patch 0.217.22 notes one exception to it: mobs spawned by a boss still attack, because the boss is already fighting you. playerevents is the modifier Iron Gate's patch notes call player-based raids, and nobuildcost is No Build Cost.
The in-game World Modifiers screen has more checkboxes than these four. Patch 0.219.16, for example, moved free placement of food out of No Build Cost into a separate No Craft Cost modifier. Iron Gate's server guide documents -setkey values for the four keys above only, so those are the ones to rely on for a dedicated server.
- nomap: no map for anyone on the server
- passivemobs: passive mobs, except mobs a boss spawns
- playerevents: player-based raids
- nobuildcost: No Build Cost
Writing the start line
World modifiers go on the same line as the server's other options, after -name, -world and the rest. Write the preset first, then each modifier, then each key. A server that wants Hard combat but no raids and no map would end its line with -preset hard -modifier raids none -setkey nomap.
On your own machine, that line is in start_headless_server.bat on Windows or start_server.sh on Linux. Iron Gate suggests editing a copy of the file, because a Steam update resets the original. On a rented server, the same options go in the startup settings of the control panel. Our Valheim server settings generator builds the whole line, with the preset always first, and leaves out any value Iron Gate does not list.
The server reads the line when it starts, so restart it after every change. If you are bringing an existing world across at the same time, moving a Valheim world to a dedicated server covers the -world name that has to match.
Changing modifiers on a world that already exists
Iron Gate gives two routes besides editing the start line. Patch 0.217.22 added a -resetmodifiers start parameter for dedicated servers. The same patch made a set of console commands available to admins on a server: setworldpreset, setworldmodifier, resetworldkeys, setkey, removekey, resetkeys and listkeys, which displays the list of keys on a dedicated server.
The console opens with F5. To use admin commands there, your Platform User ID has to be in adminlist.txt in the server's save path, one ID per line in the case-sensitive format [Platform]_[User ID]. You can read the ID from the server log or the F2 panel in game.
Take a copy of the world before changing a running world's difficulty, especially DeathPenalty or Resources, and tell your players what is changing. For mods, memory and the rest of the server's settings, see our Valheim mods and RAM guide and the Valheim game page.
- -resetmodifiers: start parameter added in patch 0.217.22
- setworldpreset and setworldmodifier: change modifiers from the console
- setkey, removekey and resetkeys: manage the checkbox keys
- listkeys: shows the keys set on a dedicated server
- Admin console commands need your ID in adminlist.txt