Multiplayer and Server

Who needs the mod

InvisibilityPotion is set to EveryoneMustHaveMod. The server and every client need it, with the same major.minor version (0.3.x with 0.3.y works, 0.2 with 0.3 is refused). A vanilla client cannot join a server running the mod, and a client with the mod cannot join a server without it.

Jötunn version rule

Server and clients need the same Jötunn version down to the patch number. The mod is built against Jötunn 2.30.0 and BepInExPack Valheim 5.4.2350. A mismatch shows a "Mod version mismatch Jotunn" dialog and the server disconnects the client. The BepInExPack version is not checked.

Dedicated server

1. Stop the server.
2. Install BepInExPack Valheim in the server folder (on Linux this includes start_server_bepinex.sh).
3. Put Jotunn.dll (2.30.0) into BepInEx/plugins/Jotunn/ and InvisibilityPotion.dll into BepInEx/plugins/InvisibilityPotion/.
4. Start the server with BepInEx's start script instead of the plain one. Copy the script first and put your own arguments (-name, -port, -world, -password, ...) into the copy, because BepInExPack updates replace the original. Run it from the server folder.
5. If you use systemd: point ExecStart at the copied script, set WorkingDirectory to the server folder and use KillSignal=SIGINT so the world is saved on stop.
6. Check BepInEx/LogOutput.log for Loading [Jotunn 2.30.0], Loading [InvisibilityPotion 0.4.x] and Patch health: 23 targets patched, 0 missing.

No LogOutput.log means BepInEx did not load: wrong start script or wrong working directory.

The server's config file is the one that counts: gameplay values are pushed to every client on join and on change. See Configuration for the exceptions (recipes and world-generation values are read from each machine's own file).

What tier III does on the network

• The server hides the player's real position from other players (no position updates) and removes the map pin. This is why the server needs the mod.
• Other clients see no nameplate and no player-list entry for the hidden player.
• A player wearing Allfather's Eye sees the nameplate, veiled body and real position, but never a map pin.
• Server switch: AllowPvpInvisibility in [General].

Known limitations

• Mumble positional audio sends your position to other Mumble users with positional audio and can reveal a tier III player. Outside the mod's control; tell PvP groups.
• Map pin: hidden players have no pin for others, and goggles never show one.
• Admin-only values: only admins can change gameplay values in game.
• Recipes are local: read at startup from each machine's file, not synced.
• Retrofit is server-side: wild plants for zones generated before the mod are placed by the server (RetrofitExistingZones); the server's config value counts, and the server does the work (one zone per player per 0.1 s, only zones near players). The server log shows plants: retrofit zone (x,y): N placed per zone with new plants and, every 25 evaluated zones, a summary line with the counters. RetrofitReportOnly = true is a dry run (counts, places nothing).
• Mods that replace AI perception, rewrite ZDOMan.SendZDOs, or replace nameplates may break hiding. See the FAQ for compatibility.

Admin console commands

Open the console with F5 (the game needs -console in its launch options). On a dedicated server only admins can use them; the host and a local game always can. Every line also goes to BepInEx/LogOutput.log.

• ip_plants [radius=64]: every hidden plant in range with distance, direction, stage and growth timer; lichen tree counts; every sprout of this mod with its status and grow time. ip_plants nearest sets a map pin on the nearest one, ip_plants unpin removes it.
• ip_retrofit: state and counters of the zone retrofit. ip_retrofit here checks your current zone now (server/host only), ip_retrofit reset forgets which zones were checked this session.