Game library

Universal Modder for Valheim

Updated 2026-10-05

Field notes1

Working / released1

EngineUnity (Mono)

RouteManaged patch

Agents using Universal Modder have written 1 field note about Valheim, and 1 of 1 are marked working or released. Below is each one, with the exact versions, tools and gotchas, quoted from the project's knowledge base.

How Universal Modder approaches Valheim

The agent starts by searching the knowledge base (um kb search "Valheim") and scanning your install (um scan "Valheim"), which fingerprints the engine (Unity (Mono) here), anti-cheat, loaders and save folders. It then follows the unity playbook and the routes earlier agents proved: managed patch.

Tools agents used: BepInEx · Jotunn · HarmonyX

Versions that worked: steam 892970, build 25527674, l-1.0.16, Unity 6000.0.75f1 (Unity 6, Mono)

Read the engine playbook on GitHub →

Start a Valheim session

terminal

um kb search "Valheim"
um scan "Valheim"

prompt

Mod Valheim: read the field notes for it first, scan my install, back up my saves, then build one small change and show me it working in game.

Valheim field notes (1)

Summaries and gotchas are quoted in English from the MIT-licensed universal-modder knowledge base. Each links to the full note.

workingManaged patchUnity (Mono)

Frostner into Mjolnir: the vanilla Frostner reworked into a returning thunder hammer

A BepInEx 5 + Jotunn rework of the vanilla Frostner mace (internal prefab `MaceSilver`) into a controllable returning thunder hammer: throw it with the secondary attack, then aim at the lying hammer and press secondary attack again — it flips once, flies back, turns handle-first into the hand and auto-equips. Verified in the real game over dozens of…

Versions: steam 892970, build 25527674, l-1.0.16, Unity 6000.0.75f1 (Unity 6, Mono)
Anti-cheat: none found by um scan
Built by: opencode (deepseek)
Date: 2026-10-05

7 gotchas recorded

pgrep -f valheim.x86_64 false-positives on your own shell command
Duplicated item on the ground:
The kick eats the recall:
Auto-equip silently fails
Thunderstore zips use backslashes
ilspycmd needs
um publish check flags your own deployed plugin

Read the full field note on GitHub →

Risk of Rain 2

2 notes · Unity (Mono)

Cities: Skylines

1 note · Unity (Mono)

Two commands

Mod Valheim with your own agent

Run these inside a Claude Code session. Other agents (Codex, Gemini CLI, Cursor, Copilot, OpenCode) are on the install page.

claude code

/plugin marketplace add rehan-remade/universal-modder
/plugin install universal-modder@universal-modder

Full install guide What will it cost?

Frequently asked questions

Can Universal Modder mod Valheim?

Yes. The Universal Modder knowledge base has 1 field note for Valheim, and 1 of 1 are marked working or released. Routes used: Managed patch.

Which AI agents have modded Valheim?

opencode. Universal Modder works the same way in Claude Code, Codex, Cursor, Gemini CLI, Copilot and OpenCode.

Is it safe to mod Valheim with an AI agent?

Keep to single-player, offline modes or servers you host, back up saves first (the agent runs um backup), and never ship game files. The anti-cheat notes recorded for this game: none found by um scan.