Hi @benxzmn, I will try to be detailed in guiding you as I don't know how much technical knowledge you have.

I recommend downloading this script by right-clicking the "Raw" button in the top right of this page, and choosing "Save Link As...". This way you can be sure you did not miss any letters when copying it. To make the steps easy I also suggest moving the file to the same directory as the game save files, otherwise you need to use the full file paths (instead of just the file names) when running the script.

The script should be run with Node which you will need to download and install.

1. Open a command prompt (cmd or PowerShell). Not before installing node, as the node command will then not be recognized
   • Open the start menu and search for cmd, it should show the application Command Prompt
   • or, press the keyboard keys Windows (flag) and x together then choose the command prompt in the list
2. Change directory in the command prompt to where you saved the file (in this case the save file directory)
   • Write cd "%userprofile%\AppData\LocalLow\Sabotage Studio\The Messenger" and run the command by pressing the Enter keyboard key
3. Write the following, make sure to add a space character after each:
   1. node
   2. File path/name to the script (the_messenger_save_decoder.js)
   3. Path/name of the encoded save file (saveGame.txt)
   4. Path/name of the decoded save file (saveGameDecoded.txt, can also be saveGame.txt to overwrite the file but just to be sure I would recommend against it)
   • If you are using cmd you can also drag-and-drop the file onto the window and it will automatically type the path for you
4. Run the command which should now look like this: node the_messenger_save_decoder.js saveGame.txt saveGameDecoded.txt. The script reads the first file, and overwrites the second file. If you see any error message when running this command please share it
5. Open the decoded file saveGameDecoded.txt in a text editor (such as notepad, vs code. Do not use Word or similiar word processors as they may change the file unpredictably), and make your adjustments
   • Note that this file contains save data for all three save slots, if you are using multiple slots make sure you edit the correct one
6. Run the command again, but this time switch the order of the encoded/decoded save file names: node the_messenger_save_decoder.js saveGameDecoded.txt saveGame.txt
7. Restart the game and enjoy your modified save file

I have not explored the format beyond decoding it, for example what items have what IDs, so unfortunately I can not advise you on what to change to get certain results. I have only made the adjustment mentioned in the previous comment, which I inferred from the naming of the data.

Hope this will be of use to you!

Hey @aqt thanks a lot for this tutorial. It helped a lot. Ive gotten it to work and I achieved the Achievement.
I wish you the best.

Modified to parse the JSON correctly when encoding back(in case it auto formatted for whatever reason, etc):

#!/usr/bin/env node

/*

If you run the script on an encoded file it will output a decoded file and
vise versa, because the action used to encode/decode is identical. The save
file format when decoded is plaintext JSON, which you can edit with your
favorite text editor.

You can find the save file at the following path. Please make a backup of the
file before you make any adjustments to it!

%userprofile%\AppData\LocalLow\Sabotage Studio\The Messenger\saveGame.txt

*/

const fs = require("fs");

if (process.argv.length < 4) {
  console.log("Required arguments: <inFile> <outFile>");
  process.exit(1);
}

const inFile = process.argv[2];
const outFile = process.argv[3];

function convertFile(inFile, outFile) {
  let data = fs.readFileSync(inFile, "utf-8").replace(/\r\n$/, "");
  try {
    // Try to parse as JSON and minify
    const parsed = JSON.parse(data);
    data = JSON.stringify(parsed);
  } catch (e) {
    // Not JSON, use as-is
  }
  let convertedData = "";

  for (const char of data) {
    const charCode = char.charCodeAt(0);
    const isOdd = charCode % 2;
    const nudge = isOdd ? -1 : 1;

    const newCharCode = (charCode ^ 128) + nudge;

    convertedData += String.fromCharCode(newCharCode);
  }

  fs.writeFileSync(outFile, convertedData + "\r\n");
}

convertFile(inFile, outFile);