The port of the legendary indie game Undertale to the mobile platform allowed fans to go through Frisk's adventures anywhere. However, a mobile operating system has its own data storage features that are different from a PC. Players are often faced with the need to find specific files in order to transfer progress to a new device or create a backup copy before risky experiments in the Genocide root.
In this article we will analyze in detail the file structure of the game, explain how to access hidden directories on modern versions of Android and consider the nuances of working with files file0, file1 and file2. Understanding where the data is physically located will give you full control over the game process.
Before any manipulations with save files, be sure to create a copy of them in cloud storage or on your computer to avoid irretrievable loss of progress.
Standard path to the game directory
By default, game files are located in the internal memory of the device. The path to them is standardized for most assemblies released through official application stores. You will need any advanced file manager that supports working with root or system folders, since the standard explorer can hide part of the structure.
The main directory is located along the following route: Android/data/com.tobyfox.undertale/files. This is where all configuration data and saves are stored. Please note that on devices with Android 11 and higher, access to the folder Android/data can be restricted without granting special permissions or using a PC.
Inside this folder you will find several key items. The most important files are those responsible for save slots. Their names do not contain extensions, which sometimes confuses newbies. The system determines their type by content, not by name.
- 📂 file0 —the first save slot, used by default when starting a new game.
- 📂 file1 —the second slot, available for creating an alternative passage.
- 📂 file2 —the third save slot for parallel game sessions.
- 📂 system_undertale.ini —system settings file games, including volume and controls.
Access features on Android 11 and later
Starting with the eleventh version of the mobile operating system, Google has tightened its access policy file system as part of the Scoped Storage function. This means that regular Explorer applications can no longer easily access the folder Android/data. When you try to navigate, you may see an empty directory or an access error message.
To bypass this limitation, it is recommended to use specialized file managers, such as CX File Explorer or Solid Explorer. These applications request special system permission the first time they access a protected folder. After confirmation, you will have full access to read and write game files.
⚠️ Attention: Do not try to forcefully change access rights to system folders through root access without understanding the consequences. This may interfere with other applications and cause system instability. Use standard methods for providing access through the file manager interface.
If you do not have the opportunity to install third-party software, you can connect your smartphone to your computer via a USB cable. In file transfer mode (MTP), the computer sees the memory structure differently, and Scoped Storage limitations often do not apply to an external connection. This is the most reliable way to copy save files without installing additional software on your phone.
Structure and purpose of save files
Save files Undertale are binary data encrypted with a simple algorithm. The game checks checksums upon loading, so simply editing text in Notepad will result in file corruption and a "Corrupted" error. However, understanding the structure helps to copy them correctly.
Each save file contains information about the current location, inventory, character statistics (LV, HP, ATK, DEF) and, most importantly, plot flags. It is the flags that determine what events have already occurred and how NPCs react. When you transfer a file to another device, the game considers that you continued to play on this device.
| File name | Description | Size (approximate) | Can be edited |
|---|---|---|---|
| file0 | Main save (Slot 1) | ~1-5 KB | No (hex editor required) |
| file1 | Additional saving (Slot 2) | ~1-5 KB | No (required hex editor) |
| file2 | Additional saving (Slot 3) | ~1-5 KB | No (hex editor required) |
| system_undertale.ini | Graphics and sound settings | ~1 KB | Yes (text format) |
In addition to the main slots, the folder may contain a file fun.ini. He is responsible for generating random events and the appearance of secret characters such as Gaster. Deleting or changing this file may reset unique encounters that will no longer appear in the current playthrough.
What is the fun.ini file?
This file contains a numerical value from 1 to 100 that determines the probability of rare events occurring. If the value matches certain numbers (eg 66), events are triggered. Changing it manually is not recommended, as the game may overwrite it upon startup.
How to make a backup copy of progress
Regularly creating backups is a golden rule for any player, especially before completing difficult sections or experimental routes. The process of copying files is simple, but requires care not to mix up the slots.
First, open the file manager and go to the folder Android/data/com.tobyfox.undertale/files. Select the files file0, file1 and file2that correspond to your active saves. Do not copy system files if you do not want to transfer control settings.
☑️ Checklist for creating a backup
Copy the selected files to a safe location. This could be a separate folder in the internal memory, for example Internal Storage/UndertaleBackups, or cloud storage like Google Drive. When restoring, you will simply need to return files with the same names back to the game directory, replacing the existing ones.
If you rename file0 to save1, the game simply will not see it and will offer to start a new game. The naming structure is strictly fixed by the game engine.
Transferring saves between devices
A common situation: you bought a new smartphone or want to continue the game on a tablet. Transferring saves Undertale between Android devices is carried out by directly copying files. There are no cloud saves in the game itself, so manual transfer is the only option.
First, make sure that the game is installed on the target device and launched at least once. This is necessary to create the initial folder structure. Then connect your old device to your PC and copy the save files to your computer.
⚠️ Attention: Make sure that the game versions on both devices are the same. Transferring a save from an updated version to an old one may cause critical errors or application crashes due to data incompatibility.
Connect the new device and paste the copied files into the appropriate directory Android/data/com.tobyfox.undertale/filesagreeing to replace existing files. After this, launch the game - you should see a continuation menu with your progress.
Successful transfer depends on an exact match of paths and file names. Any deviation in the name of the folder or file will result in the game creating new empty saves instead of loading old ones.
Possible problems and their solutions
Sometimes players are faced with the fact that the game does not see save files even after correct copying. Most often this is due to access rights or data caching by the system. In such cases, clearing the application cache through the Android settings helps.
Go to Settings → Applications → Undertale → Storage and click the "Clear cache" button. Do not click "Clear data" otherwise you will delete all saves! After clearing the cache, restart the game and check for slots.
Another common problem is file corruption during transfer. If the game reports a corrupted file, check the size of the copied file. It should not be 0 KB. Try copying the files again using a different transfer method (for example, via cable instead of Bluetooth).
If you are using emulators or custom builds of the game, the file paths may differ. In such cases, look for the folder with the name of the game in the root of the internal memory or in the folder Games. Always check the documentation for the specific version of the port.
Is it possible to edit gold and experience in save files?
Technically it is possible, but this will require a hex-editor on your phone or PC. Simply changing numbers in text form will corrupt the file. In addition, the game has built-in anti-cheat protection: if inconsistencies are detected, it can block achievements or reset progress.
What to do if the Android/data folder is empty?
On Android 11+ this is normal behavior for the standard Explorer. Use an application Files by Google with the display of hidden files enabled, or install a third-party manager like Solid Explorerwhich will ask for special permission to access this directory.
Are saves synchronized via Google Play Games?
No, on mobile version Undertale there is no built-in support for cloud synchronization via Google Play Games. All data is stored exclusively locally on the device, so manual backup is the only way to protect progress.
How to reset all saves to factory settings?
For a complete reset, delete files file0, file1, file2 and system_undertale.ini from the game folder. You can also delete the application itself and install it again - this is guaranteed to clear all local data and return the game to its original state.