UNDERTALE: Debug Mode

Overview

UNDERTALE has a recently discovered (kinda old) debug mode that has a lot of commands that can test the game or give you an upper edge in battles. This guide will go over all the commands, and how to trigger the debug mode.

Introduction

Hello, and welcome to my guide about the debug mode for UNDERTALE. Since you’re just a reader and I don’t know anything, I’m just going to assume by clicking this guide you have:

beaten UNDERTALE
looking for something new to do with the game
playtesting

If any of these answer “yes”, then this is the guide for you!

NOTE: This guide might, MIGHT, spoil some of the game for some people. If you haven’t watched videos about the game or beaten it, please, don’t read further.

Otherwise, MAKE SURE YOU BACK UP YOUR FILES BEFORE DOING THIS! If you come up to me and complain that your UNDERTALE is broken after doing this, I will not be responsible for your game breaking.

Despite that, let’s begin.

Extracting UNDERTALE.exe

Note: You can skip this part if UNDERTALE is already extracted. You can find this by checking for a bunch of .oggs in the folder you start with. If there’s a bunch, it’s already extracted.

So, you’ve read this far, and you want to get to UNDERTALE’s debug mode. Well, first thing’s first, you’re going to have to go to your local content for UNDERTALE. This is usually found at this location:

C:/Program Files(x86)/Steam/steamapps/common/Undertale.

Another alternative if you don’t know where you’ve installed Steam, go to your Library, right-click on UNDERTALE and press Properties. Go to “Local Content”, and then click “Browse Local Content”. It will then open up an explorer window leading you to the executable.

Next, you should already have a zip extractor, like WinRAR.[www.rarlab.com] That’s what I used to extract the executable. Go to the folder, and right-click on the executable. Then, click “Extract Here” to extract it to the folder it’s currently in. Although it’s possible, I don’t recommend it, as extracting it will extract a new UNDERTALE.exe, so you should try pressing “Extract Files” and select where it should be extracted.

WARNING: If you go past this point without backing up your game, you may break your game. Proceed with caution. I know I didn’t.

Once you’ve extracted UNDERTALE.exe, it should ask you if you want to replace a new executable with the old one. Rename the new one. You’ll need it for later. Once you’re done extracting, rename the new executable (whatever).exe to UNDERTALE.exe, and replace it in your UNDERTALE directory. But, this doesn’t enable debug mode. What REALLY enables debug mode is actually in data.win.

Hex-editing Data.win

So, you’ve made it this far and you want to enable debug mode. Well, if you have already extracted UNDERTALE.exe and got data.win, you’ll need a hex editor. I personally would prefer HxD,[mh-nexus.de] but anything will work as long as it can hex-edit. Open data.win with your hex editor, and find 0x725D8C (00725D8C) or 0x725B24 (00725B24) if you’re running an older version of the game, and change it to 01. Finding this might be challenging at a glance, but the easiest way to do it (with HxD) is to right-click at the left of the screen where all the numbers are listed, and select “Select block.” Once you do that, a box should pop up. Put in 00725B24 as the staring offset and the ending offset, and press OK.

Once you’ve changed the value, go to the folder you have extracted UNDERTALE and find the executable that was in the UNDERTALE.exe you have extracted. For reference, the executable you extracted is around 3,163 KB. The executable you usually play UNDERTALE with is usually way bigger because it has all the files, including data.win inside of it. Replace the big executable with the small one, and start the game. If it has worked, you should have all the debug commands! Congratulations. After this, if you want to revert, just change the value back to 00.

Debug Mode Features

All of the Fun events will trigger, regardless of what your Fun level is set in your save file.

Hotkeys

There are a bunch of keyboard commands in specific fights and places that you can trigger by pressing a key on your keyboard. Here are the commands that are discovered so far:

Key

Effect

Opens a dimensional box.

G (in a shop)

Adds 5000 gold.

Opens an unused dialog to take out items from a dimensional box.

Ditto, but to put away.

Opens the save dialogue.

Loads your save file instantly.

Increases your murder level to 1, pretty much starts a genocide run.

Sets the game’s current speed to double the normal amount, and caps the FPS at 60 for the duration of a room.

Toggles room speed between normal and fast.

When pressed in rapid succession, will restart the game.

Toggles Undyne phone calls. Tints the character blue if enabled, yellow if disabled.

Shows collision boxes for all rooms.

Slows the game down to 10 FPS.

Increase battle group by 5. Doesn’t roll over to 0 after 256. Related to the Home key. List of battle groups here.[web.archive.org]

Backspace

Increases walk speed when held down.

Pg Up

Increases your steps by 100.

Pg Down

Decreases your steps by 100. Just kidding, it sets your attack in the STAT menu to 989, but it is purely cosmetic.

End

Plays the next monster (Flowey in a genocide run) dialogue from New Home.

Home

Starts a battle with the current battle group. Default battle group is 80 (Mettaton before going EX). If you want to change the default, use Cheat Engine to look for doubles, scan for zeros, press the 5 key and look for five, press it again and look for ten, until you get to one battle. To get to battles lower than 80, type a negative number (i.e. 81, 80, -79). Thanks CorpseLicker.

Insert

Teleport to the next room in the room list. Places you in a very specific spot.

Del

Teleport to the last room in the room list.

Places system_information_962 in your save folder. After the game is reset, it puts you on the black screen after completing a genocide run. I suggest you don’t use this key.

Adds 500 gold, any time, anywhere.

Stops any sound and music currently playing.

F10

Disables collision in all rooms.

F11

Teleports you to the room after Papyrus’ boss fight (room_water1.)

F12

Restarts the room.

R + 6

Teleports to the Ruins tile puzzle room (room_ruins2.)

T + 6

Teleport to outside of the Ruins (room_tundra1)

W + 6

Same as F11.

F + 6

Teleport to Hotland’s cooler room (room_fire2)

E + 6

Teleport to New Home’s entrance (room_castle_front)

Y + 6

Teleport to the True Lab entrance (room_truelab_elevator)

Battle-Specific Hotkeys

There are also battle shortcuts, here are the discovered battle commands:

Halves game speed. Cannot go below 1 FPS, or the game will crash.

Doubles game speed. Cannot go past 2x normal game speed. Crashes the game if it pressed too many times.

Shortens the current enemy’s turn.

Extends the current enemy’s turn.

Sets the game speed to double its normal speed.

Slows the game down to 10 FPS.

Delete

If you can’t beat Sans, this key is for you. Sets your HP to 999 for the current fight. (also your HP is above max next fight)

Sets mercy to 0 (can’t be spared) and attack to 9999.

O + P

Sets mercy to 9999, enabling the spare option. Some enemies that cannot be normally spared turn into Aaron. (protip: you can’t spare Sans.)

Area Specific

During the first time you meet Sans, press J during the cutscene to zoom in on Sans, and crash the game. (Or your game could just completely glitch out.)

The reflections in the puddles of Waterfall can be changed if you press Spacebar, to an unknown CHARActer, shown in the picture below.

If you climb Monster Kid with debug mode enabled, numbers will appear over Monster Kid’s head, starting from -1 and 0. It appears to show Monster Kid’s state, but the numbers meanings are unknown. A picture of the numbers are shown at the bottom.

Fight Specific

Lesser Dog

Key

Command

Extends Lesser Dog’s neck. Lesser Dog will go where no Dog has gone before with this command.

Papyrus

Key

Effect

Spacebar

Sets Papyrus’s next attack and dialogue to “THE KING WILL TRIM A HEDGE IN THE SHAPE OF MY SMILE!!!”

If pressed when you are blue, Papyrus will not attack you and will say “…” if you try to spare or attack him.

Shyren

Key

Command

Increases the emotion variable, used during the fight to affect her status.

Mad Dummy

A red number starting from 300 appears attached to the right of the Mad Dummy, indicating its health. Pressing A will set the number to 180, make the dummy float around, and make his next attack his final attack. A picture of this is attached at the bottom.

Debug Mode Features, Part 2

Undyne

Undyne CAN’T be spared with the combination O + P.

Key

Effect

Sets HP to 999.

Decreases turn counter by 1.

Asgore

A turn counter counts up from 0 in the top left corner of the screen. The higher the counter is, the harder Asgore’s attacks are and the less defense Asgore has. Press A to decrease, press S to increase. If above 20, it is set back to 20 each time Asgore does his orange-blue attack. If set manually to 22 or below 1, it will crash the game when Asgore attacks. A picture of the number counter is shown below.

Flowey

The text “debug” comes down on the right side of the screen along with Flowey, and stays the whole fight. The intro and game over screens are skipped after the first death.

Key

Effect

Creates system_information_962 in the save folder.

Home

Attack Flowey instantly. Does 6000 damage if all soul indicators are darkened.

Pg Up

Darkens the soul indicators in order, increasing ndamage and affecting the next soul battle. Disables darkening when all are darkened, and the next time a soul battle occurs, the game will crash.

Right Shift, Left Shift, X

Darkens the soul indicators in order, increasing damage and affecting the next soul battle. Does not crash the game when all are darkened.

Starts the battle instantly during the intro. Does not stop the intro, so you cannot move and the attacks will miss you unless Flowey is close.

Slows the game down to 10 FPS. If used in Flowey’s death state, starts the attack after Flowey’s health is restored.

One burst of three stars from each eye.

One burst of seven stars from each eye.

Makes Flowey laugh and restart his attacks, including in a soul battle.

Purple Soul fight (books)

Green Soul fight (frying pan)

Toggles flamethrower.

Saves battle state. Shows “FILE 2 SAVED” in the bottom left corner.

Doubles game speed. Lock on pellet attack.

Orange Soul fight (glove.)

One hand-gun attack.

Yellow Soul fifght (gun)

Aqua Soul fight (knives)

Loads battle state. Shows “FILE 2 LOADED” at bottom left corner. If there is no save, it will crash the game.

Toggles Flowey’s mouth flap waving around.

Single vine attack. Will trigger more if held down.

Single Flowey Bomb.

Ball of teeth/dentata attack.

Asriel

Key

Effect

Toggles Asriel’s floating around and staying still above the middle of the screen.

Space

Same as above, but closer to the top. Asriel must be still for any of the below keys to work. Attacks stack and start instantly.

Chaos Buster/Chaos Blaster

Shocker Breaker/Shocker Breaker II

Chaos Saber/Chaos Slicer, slows the game down to 10 FPS.

Star Blazing/Galacta Blazing

Hyper Goner

Undyne the Undying

Undyne cannot be spared with the combination O + P.

Key

Effect

Sets HP to 999.

Decreases turn counter by 1.

Sans

Sans can’t be spared with the combination O + P. If you try to, you’re gonna have a bad time.

Key

Effect

Set Sans’ next attack to his special attack.

Sets Sans’ next attack to the part where he spares you.

The End

Well, that’s it for the guide. If I messed up or I didn’t put something down that I should, give me a message and I’ll fix it! If you liked this guide, feel free to give me a like or dislike of some sort. Other than that, I hope you enjoyed my guide, and thank you for reading or not reading. If you can, you should also check out my other guides, such as my guide about editing your save file for VVVVVV.

[link]

Sources

All pictures and debug commands are taken from TCRF’s great page on Undertale.[tcrf.net]. Everything copyrighted goes to their respectful owners.

Undertale Guide

Overview

Introduction

Extracting UNDERTALE.exe

Hex-editing Data.win

Debug Mode Features

Debug Mode Features, Part 2

The End

Sources