Cave Story’s Secret Santa: Save Editing Guide

You should quit the game before doing this. Any changes you make will not apply if you don’t restart the game.

While the .dat extension might lead some to believe the file contains binary data, it’s actually plaintext. However, if you try opening it in a program like Notepad, you’ll be greeted by a jumble of letters and numbers. Something like this:

eyJtX1N0YWdlSW5mbyI6W3sibV9OYW1lIjoiU1RBR0VfTkFNRV9TQU5UQVNfSE9VU0UiLCJtX0lzD...
...you get the point.

That’s because the save file is Base64 encoded. You’ll need to use a tool that can decode Base64 to transform it into something usable. You can easily find a decoder by typing something like ‘base64 decode’ into your search engine of choice.

After decoding it, you will end up with something more readable, but pretty cramped. Something like this:

This is a minified JSON file. While you could start reading it and editing as it is, it would be more convenient if you prettified/formatted it first. You can also search for a tool that does this. The end result is the exact same JSON file, but presented in a much more appealing way. Something like this:

{
  "m_StageInfo": [
    {
      "m_Name": "STAGE_NAME_SANTAS_HOUSE",
      "m_IsComplete": true,
      "m_Time": "0:16",
      "m_Bonus": "NONE",
      "m_Index": 2
    },
    {
      "m_Name": "STAGE_NAME_MALCOS_HOUSE",
      "m_IsComplete": true,
      "m_Time": "0:17",
      "m_Bonus": "NONE",
      "m_Index": 17
    },
...etc etc.

At this point, you can start reading the save file’s content and make guesses as to what’s what. You can start modifying it as well, if you wish. Read the next section of the guide for a description of each part of the save file.

If you did any modifications to your save, you will now need to apply all the steps to opening the file in reverse in order to save it and see it applied in-game. This consists of:

1. Minifying the JSON file. You can also search for a tool that does this. I don’t think it’s strictly necessary to do this, but I recommend doing it anyways.
2. Encoding it to Base64. Usually, any tool that can decode Base64 will also have a complimentary utility to encode to Base64.
3. Replacing the contents of secret_santa.dat with the Base64 encoded text and saving it.

Afterwards, you should be able to start the game up and select ‘CONTINUE’ to load up the save along any changes you’ve made!

The following are found for each stage listed in m_StageInfo.