Undertale: Developer Mode

Developer mode allows the player to influence the gameplay.

Developer mode can be enabled, if you change in line 00725D8C (in version 1.001), or 00752B20 (in version 1.0), or 7748C4 (in version v1.08) everything 00 on 01 in data.win (для Linux assets/game.unx) using a special program (for example, HxD on Windows or game.ios on Mac OS X.).

If you are playing on the Steam version and this method does not work for you, then try deleting the steam_api.dll file.

Button Effect
G Opens Dimensional Chest
G (only works in Temmie's shop) Gives 5000G
O Allows you to take things from the chest
I put things in the chest
S Allows you to save
L Loads your save
M Increases Kill Level(Murder Level) on 1
F Increases FPS up to 60
P Makes the room speed faster
R If you press 7 time, will reload the game
U Changes the protagonist's costume
V Shows the boundaries of the room
W Decreases FPS to 10
5 Increases the group of battles by 5
Backspace
Increases speed (you need to hold down the button)

Pg Up Increases steps by 100
Pg Down Makes an attack 989
End Includes the beginning of the tale of the two Froggits (Flowey in the Genocide Path) from the New House
Home Starts a fight in a group of battles. Default 140 (Yes Sorry) in version 1.0 or 80 (Mettaton) in version 1.001. Change 0x9F553C (in version 1.0) or 0x9EB414 (in version 1.001)
Insert Teleports to the next room. If the protagonist is in the Real Laboratory, then Insert will teleport him to the room 264 (only there will be no symbols)
Delete Teleports to the previous room. If the protagonist is at the very beginning, calls the loading screen
F3 Creates a file "system_information_962" in the game folder (consequences of the genocide path)
F7 Adds 500G
F9 Stops all music, which plays
F10 Allows you to walk through walls (not objects!), also allows you to walk during dialogues and cutscenes
F11 Teleports to room_water1
F12 Breaks down the barrier (triggers the consequences of destruction: if you are in rooms, where monsters should appear with a grateful speech, then they will appear there, merchants also change their speech to that, which appears after the destruction of the barrier). Moreover, the game process does not change in any way., and the events taking place will correspond to the ending, which you are walking
R + 6 Teleports to room_ruins2
T + 6 Teleports to the exit from the ruins room_tundra1
W + 6 Also, as F11
F + 6 Teleports to Hotland (room_fire2)
E + 6 Teleports to the New Home (room_castle_front)
Y + 6 Teleport to the Real Laboratory (room_truelab_elevator)
Facilitate battles

Button Effect
1 Decreases speed (if very slowly, then the game will close)
2 Increases speed by 2x
8 Reduces the opponent's turn
9 Increases the opponent's turn
F Same, what u 2
W Decreases FPS to 10
Delete Changes health to 999
F6 The next attack will deal a lot of damage
O + P Includes mercy (you need to press two buttons at the same time)
Special
First meeting with Sans
Press J, to make a joke effect. After that, the game will close.

Chara in reflection
If you press the space bar, then someone will be seen in the reflection of the water, like Chara. You cannot use an umbrella., otherwise nothing will work.

For battle
Small Dog
Button Effect
J Enlarges the neck
Papyrus

Button Effect
Spacebar Before the next attack it will be said: "THE KING WILL SHOVE THE HEDGE IN THE FORM OF MY SMILE!!!», and after that, how did your soul turn blue, some dialogs will also be changed
O He will just say: «…»
Шайрена

Button Effect
3 Changes her emotions
Mad Dummy
There will be numbers on the right, which reflect his health in battle.

Andain
It cannot be skipped by pressing O + P.

Button Effect
7(Delete) Changes health to 999
Space (space) You miss Undyne's attack.
A Decreases the counter by 1
Asgor
A counter appears on the top left. The higher it is, the stronger the attacks.

Photoshop Flowy
The "debug" text will be visible on the right side of the screen.

Delete button (999 lives) does not work.

Button Effect
Home Attacks Flowey instantly (if all souls are activated, to na 6000 damage)
Pg Up Activates one of the souls in order
Delete Flowey's health bar does not decrease when dealing damage (In the third stage of the battle)
Right Shift, Left Shift, X Same, as Pg Up
Q Instantly starts combat
W Slows down the game by 10 FPS
E Stars fly out of each eye
R 7 stars fly out from every eye
I Restarts the fight
O Fight with a purple soul
P Green Soul Fight
A Turns on the flamethrower
S Saves the fight (it will say “File 2 saved ")
F Speeds up the game by 2x
G Fight with an orange soul
H Rifle
J Fight with a yellow soul
K Blue Soul Fight
L Load fight (it will say “File 2 loaded ")
C Laser attack
V Attack liana
N Bomb attack
M Tooth attack
Shift Deactivates souls 1 time
Azriel

Button Effect
C Enables / disables Asriel's flight
Space Ditto, as well as C
G Laser
B Lightning
W Sable (reduces FPS by 10)
S Stars
H Hyper-attack
Immortal Undyne
Can't let go with O + R.

Button Effect
7 Changes health to 999
A Changes the counter to 1
Sans

Button Effect
E Special attack
W lets you spare him
Interesting Facts
If you try to spare Asgore with O + Р, gameplay will be gone.
If you attack Mettaton with F6, it will be applied 2-4 units of damage.
Activating Developer Mode is the only way to see the coffins of Decency and Perseverance.
When fighting Azriel during your turn, if you press “from”, and then press any of Asriel's attack buttons, then, during your turn he will attack you.