Fields of Mistria Item IDs – Save Editing Reference

Overview

Fields of Mistria item IDs are identifiers used to reference items when editing save files or creating mods. Two distinct identifier systems exist in the game: numeric IDs (short numbers used inside the save data) and internal names (human-readable strings that uniquely identify each item). Understanding which system you are working with matters because the save editor and modding tools expect different formats.

As of the current version, editing save files requires a decryptor created by the developers. The player.json file — which contains your inventory, gold, essence, mana, and active buffs — is stored encrypted under %localappdata%\FieldsOfMistria\saves. You must decrypt it before editing and re-encrypt it afterward.

This page consolidates what is currently verifiable about Fields of Mistria item IDs, how they are used in save editing, and what remains unconfirmed.

How Item IDs Work in Fields of Mistria

Fields of Mistria stores items in save data using a structured format. Each inventory slot contains an item reference, and empty slots are represented as {"members":[],"required_tags":[]}.

When adding an item to an inventory slot, you modify the members array to include the item's ID and quantity. A community-reported example from the Steam guide shows a stacked inventory entry:

{"members":[{"item_id":"worn_sword","amount":1}],"required_tags":[]}

Community reports indicate that the item ID used in save files is an internal name (a string) rather than a plain number. However, the exact format for all items has not been fully documented in a single public source. The Steam community guide links to a community-maintained document of item IDs, but that document is described as "disorganized" and is not hosted on an official wiki.

Numeric IDs vs. Internal Names

A GitHub repository for Fields of Mistria mods (DigUpAnything) clarifies that items have both an internal name and a numeric ID. The internal name is what uniquely identifies an item in code and save data. The numeric ID is a separate value that some tools or mods may reference.

For most save-editing purposes, you will use the internal name. If you are working with a mod that expects a numeric ID, verify which system that mod uses before editing.

Where to Find Item IDs

There is no official, complete list of Fields of Mistria item IDs published by the developers. The following sources exist, but each has limitations:

If you need a specific item ID not covered below, the most reliable method is to check the game's data files directly or consult the community-maintained Google Doc linked from the Steam guide.

How to Use Item IDs for Save Editing

Step 1: Locate and Decrypt Your Save

1. Press Win+R, type %localappdata%, and press Enter.
2. Navigate to FieldsOfMistria\saves.
3. Identify the save file you want to edit (usually the most recently modified).
4. Use the developer-provided save decryptor to decrypt the file. The decryptor is linked from the Steam community guide.

Important: Always back up your player.json file before making any changes. A corrupted save can prevent the game from loading.

Step 2: Edit the Inventory

Open the decrypted player.json in a text editor and search for "inventory". Each inventory slot is an object inside the members array. To add an item, modify the slot to include the item's internal name and amount:

{"members":[{"item_id":"ITEM_NAME_HERE","amount":NUMBER}],"required_tags":[]}

Replace ITEM_NAME_HERE with the actual item ID and NUMBER with the desired quantity.

Chest inventories are stored separately. Community reports place them in either playerhome.json or farm.json, depending on where the chest is located. The items in chests appear under "inventories" rather than "inventory".

Step 3: Edit Gold, Essence, and Mana

The same player.json file contains your resources:

• Gold: Search for "gold" (with quotes) and change the value.
• Essence: Search for "essence" (with quotes) and change the value.
• Mana: Search for "mana_current". One fully charged mana unit equals 4.0.

Step 4: Re-encrypt and Test

After editing, re-encrypt the save file using the same decryptor tool, then launch the game to verify your changes.

Uses for Item IDs

Item IDs serve several practical purposes in Fields of Mistria:

• Save editing: Adding or modifying items in your inventory without playing through the game normally.
• Modding: Referencing specific items in custom mod code.
• Event shortcuts: Community reports indicate that adding festival flowers directly to your inventory counts as valid entries for the Spring Festival event.
• Testing: Quickly obtaining items to test game mechanics or builds.

Version Context

Fields of Mistria has undergone significant changes that affect how item IDs work:

• Stable branch (pre-1.0): The game ran on GameMaker. Modding required tools like UndertaleModTool, and save files were edited directly as JSON.
• Beta branch / 1.0: The game moved to a new engine. Game assets are now stored in assets.zip, and save files require decryption before editing. The Steam guide notes that "anything involving game maker is now outdated" for the new branch.

Community comments on the Steam guide (as of August 2025) indicate that the modding community has largely migrated to the MOMI tool for the new engine. If you are modding on the current version, seek out current community resources rather than relying on pre-1.0 tutorials.

Known Item ID Examples

The following item IDs are confirmed through community documentation and the Steam guide's examples:

Verification note: These three IDs come directly from the Steam community guide's save-editing examples. The broader list of item IDs is not included in the collected source material, and the linked Google Doc could not be verified from this source alone.

What Could Not Be Verified

The following information could not be confirmed from the collected source material:

• A complete, current list of all Fields of Mistria item IDs.
• Whether the community-maintained Google Doc (linked from the Steam guide) is still accurate after the 1.0 engine update.
• The exact numeric ID format for items (as opposed to internal names).
• Whether item IDs changed between the stable and beta/1.0 branches.

If you need a specific item ID not listed here, check the game's data files in assets.zip or consult the Fields of Mistria modding community.

Related Pages

• Fields of Mistria Item Duplication
• Fields of Mistria Item Codes
• Fields of Mistria Earthshroom
• Fields of Mistria Essence Stone

Sources

• Modding & Save Editing Tutorial – Fields of Mistria (Steam Community)

Related Fields of Mistria Guides

• Fields of Mistria Earthshroom: Where to Find and How to Use It
• Fields of Mistria Essence Stone – Crafting, Uses, and How to Obtain
• Fields of Mistria Faceted Rock Gem: Location & Uses
• Fields of Mistria Item Duplication Guide