GameMaker Save Editing: Complete Guide to INI and JSON Files

Introduction to GameMaker Saves

GameMaker Studio (GMS) is one of the most popular game engines for 2D games, powering iconic titles like Undertale, Deltarune, Hotline Miami, Hyper Light Drifter, and countless indie hits. If you’ve ever wanted to modify your save file to unlock content, change your stats, or experiment with different outcomes, this guide is for you.

Unlike engines with a standardized save system, GameMaker gives developers complete freedom in how they store data. This means save formats vary widely, but most fall into a few common categories that our editor fully supports.

Common GameMaker Save Formats

1. INI Files (Most Common)

The ini_* functions in GameMaker are extremely popular due to their simplicity:

[player]
name="Frisk"
hp=20
maxhp=20
love=1
gold=50

[flags]
met_sans=1
spared_toriel=1

Games using INI: Undertale (PC), Deltarune Chapter 1, many indie RPGs

2. JSON Files

Modern GameMaker games often use JSON for more complex data:

{
  "player": {
    "name": "Kris",
    "hp": 100,
    "items": ["healing_item", "weapon_01"]
  },
  "chapter": 2,
  "choices": {
    "route": "pacifist"
  }
}

Games using JSON: Deltarune Chapter 2, newer GMS2 titles

3. Binary Files (ds_map_secure)

Some developers use ds_map_secure_save() which creates encrypted binary files. These are harder to edit but not impossible with the right tools.

4. Plain Text Files

Simple games may just use file_text_* functions to write raw data.

Finding GameMaker Save Files

Windows Locations

Most GameMaker games store saves in:

%LocalAppData%\[GameName]\

For example:

• Undertale: %LocalAppData%\UNDERTALE\
• Deltarune: %LocalAppData%\DELTARUNE\

Steam Cloud

Many games sync to Steam Cloud. Save locations for these:

%ProgramFiles(x86)%\Steam\userdata\[SteamID]\[AppID]\remote\

macOS

~/Library/Application Support/[GameName]/

Undertale Save Editing Guide

As the most famous GameMaker game, Undertale deserves special attention:

File Structure

File	Purpose
file0	Main save data (no extension, but INI format)
file8	Persistent data (Flowey’s memory)
file9	”True Reset” prevention data
undertale.ini	System data (fun value, settings)

Key Variables in file0

[General]
Name="Frisk"        ; Player name
Love=1              ; LV (Level of Violence)
HP=20               ; Current HP
MaxHP=20            ; Maximum HP
AT=10               ; Attack
DF=10               ; Defense
Gold=100            ; Money
EXP=0               ; Experience points
Room=12             ; Current room ID

[Kills]
kills=0             ; Total kills (affects routes)

Modifying Routes

To switch between routes, you need to modify multiple variables:

Pacifist Route Prerequisites

kills=0
killed_flowey=0
Toriel_state=1
Papyrus_state=1
Undyne_state=1

Genocide Route Indicators

kills=20+           ; Kill count in current area
Fun=66              ; Special events value

Step-by-Step Editing Guide

Step 1: Locate and Backup

1. Navigate to your game’s save folder
2. Always create backups before editing:

   cp file0 file0.backup
   cp undertale.ini undertale.ini.backup

Step 2: Upload to Editor

1. Go to our GameMaker Editor
2. Upload your save file (.ini, .json, or text file)
3. The editor will automatically detect the format

Step 3: Make Changes

For INI files, you’ll see a hierarchical view:

• Sections (e.g., [player], [flags])
• Key-value pairs under each section

For JSON files, you’ll see the full object tree.

Step 4: Download and Replace

1. Click Download Modified Save
2. Replace the original file
3. Launch the game to verify changes

Advanced: Deltarune Editing

Deltarune uses a more complex save system:

Chapter 1 (INI Based)

Similar to Undertale but with new variables:

[Actors]
actor0_Name="Kris"
actor0_HP=100
actor0_MaxHP=100

[Items]
item0="Broken_Key_A"
item1="ReviveMint"

Chapter 2+ (JSON Based)

Uses JSON with nested objects:

{
  "Recruitment": {
    "recruited_tasque_manager": false,
    "recruited_swatchlings": true
  },
  "Snowgrave": {
    "route_active": false,
    "proceed_count": 0
  }
}

Troubleshooting

”Save Data Corrupted” Error

Causes:

• Invalid INI syntax (missing quotes, brackets)
• Changed data types (string where number expected)
• Removed required sections

Solution: Restore from backup and make smaller changes

Changes Don’t Save

Possible Issues:

1. Steam Cloud: Overwriting your local changes
2. Read-only file: Check file permissions
3. Wrong file: Some games have multiple save files

Game Crashes on Load

Likely Causes:

• Invalid room ID (Room=999 for non-existent room)
• Negative HP or stats
• Missing required variables

Tips for Finding Variables

When the variable names aren’t obvious:

1. Make a change in-game and compare save files
2. Search game wikis for known variables
3. Look for patterns: kills, hp, gold, flags are common names
4. Check for base64 encoded strings (some games encode specific values)

Related Editors

Depending on the game engine, you might also need:

• Unity Save Editor – For Unity-based games
• RPG Maker Editor – For RPG Maker titles
• Ren’Py Viewer – For visual novels

Conclusion

GameMaker’s flexibility means there’s no one-size-fits-all approach to save editing, but the most common formats (INI and JSON) are well-supported by our editor. Whether you’re trying to unlock a secret ending in Undertale or just experimenting with Deltarune, the key steps are:

1. Find your save file
2. Backup before editing
3. Edit carefully with our tool
4. Test your changes in-game

If you encounter any unusual save formats or have suggestions for improvement, please contact us. Happy editing!