“Mike” is a code to Mike door in Deltarune Chapter 4 but it is not the end
Looking for a code to Mike door in Deltarune Chapter 4? It’s literally “Mike”. How is it possible? Find out. It is not the end, though, as the second door is also closed. Let’s open it together.

Some people believe that Mike is a secret boss of Golden Piano puzzle. However, Mike is also an interesting character, so why not open his door? He will not be very pleased, though.
How to unlock the first Mike door in Deltarune Chapter 4
After completing Chapter 3, a new location appears in the Castle Town. Enter the TV building to find the Mike door. If it is inaccessible for you, make sure that you have recruited everyone. You can’t enter the room without the proper code, though. Luckily for you, we know it! It is quite a difficult one to guess.
- The code to the door is 6453.
Why this code? Figuring out the key to this puzzle is the most difficult part. While you may think that the code is hidden somewhere in the game (to be honest, it probably is), the can be guessed. 6 4 5 and 3 are the numbers which stand for letters M I K E on the phone keyboard. So, MIKE is quite literally the answer to the puzzle.
How to unlock the second Mike door in Deltarune Chapter 4
It is not the end, though. You have to open the second door, too. How to do that? After going through the first door, you will quickly notice cat statues. Pat them. You will not be able to reach the tall ones, though. To do that, you need a special tool. Go right and save the Mause. The critter will turn into a hand. Now you will be able to reach the second door.
To unlock it, you must turn on your microphone and make enough sound for the door to open. The microphone statue can help you, as you can adjust the settings and sensitivity thanks to it. It will be important later. Have fun.