How to set Valheim world modifiers and difficulty

Open Worlds in the left menu and click the World rules tab. Pick a Preset, adjust any rule under Fine-tune and Switches, check the table At the next start, and click Save and restart. Valheim writes the rules into the world as it starts, and the world keeps them.

Set the rules

1. Open your server in the panel, click Worlds in the left menu, then the World rules tab.
2. Under Preset, pick one card. Each says what it does:

3. Under Fine-tune, set Combat, Death penalty, Resources, Raids or Portals. These are applied after the preset. Keep leaves that rule as the world has it.
4. Under Switches, turn on No build cost, Raids follow each player, Passive enemies or No map.
5. Read the card At the next start. It shows World and the name, and a table with Stored now and After the start for each rule. Highlighted rules change when the server starts.
6. Click Save and restart. Or Save, restart later, and the rules apply at your next restart. With the server stopped, the button is Save rules.

The message says Saved. The server is restarting, and the world takes these rules as it starts. Players are disconnected for about a minute.

Undo a rule

Keep never undoes a rule the world already has, and turning a switch off does not remove it. The page says so: Keep never undoes a rule the world already has. To go back to the game as designed, choose Normal.

1. Pick the Normal preset.
2. Set the five Fine-tune rules to Keep and turn the switches off, so nothing is applied on top of Normal.
3. Click Save and restart.
4. After the start, the table shows the rules Stored now. You can then pick Keep what the world has again.

Rules and switching worlds

Each world keeps its own rules. When you switch worlds with Play it with its own rules (recommended) ticked, the panel sets every rule to Keep, so the new world is not changed by the rules you chose for the last one. A world you upload and make active is treated the same way. See How to switch between Valheim worlds on your server.

The same rules in Game Settings

Settings, Game Settings shows the same rules as World Preset, Combat Difficulty, Death Penalty, Resource Rate, Raid Frequency, Portal Rules, No Build Cost, Player-Based Raids, Passive Enemies and No Map. Both pages change the same settings. The World rules tab adds the table of what the world has stored.

If nothing changed

See Valheim world modifiers did not change. Every option is in Valheim server settings: every option explained.