If you’ve downloaded the game Undertale from Steam to your Windows PC or Mac computer or laptop, then you might be wondering how the heck you can make it big.

There’s nothing quite as frustrating as wanting to play your game fullscreen and not knowing how to maximize it’s size on your computer.

Are you having trouble figuring out how to go fullscreen with Undertale? I was confused at first too because when I first ran the game it was locked in a small windowed mode.

undertale game

So, it took me a minute to figure out this bug, but it’s actually a super easy process to go full screen. Plus, you can probably use with any other game that has a small screen window on your laptop.

Here’s how to make Undertale full screen…

4 Ways To Get Undertale Full Screen

Based on my own testing and research, I have found that there are four different ways that you can go from that small screen version of Undertale to a fullscreen version that make use of your entire screen space.

undertale game

Keep in mind that if one of these does not work for you, then just try one of the other options. And if none of these options work for you, then just leave me a comment and I’ll see if I can help you out.

  1. Press the F4 button. This is called a function key and all of your function keys are located on the top row of your keyboard.
  2. Press the FN and F4 buttons at the same time. The FN, or function button, is usually found on the lower corner of your keyboard. On Mac computers, it will be in lowercase like this: fn
  3. Press the ALT and ENTER buttons at the same time. When you press these two buttons together, they switch you from small screen to full screen mode, no matter what game or program that you are running. Note: the ENTER button is called RETURN on some keyboards.
  4. Press the CTRL + F4 buttons at the same time. Since Mac computers don’t have ALT keys, you have to use the CTRL, or control, key instead. Of course, F4 typically works by itself on a Mac.


One of those methods should be all you need to take your game from Undertale from bite-sized to full-sized on your laptop or computer screen.

FAQs About Undertale Fullscreen

Here’s the answers to some common questions related to this.

Is this a bug in the game?

While the game developers have not officially acknowledge this as a bug that needs fixed in Undertale, players can agree that it is a bug that affects game play.

Luckily, there is the easy fix mentioned above.

undertale game

Why do I have to press FN with my F4 key?

This happens most often with laptops because a laptop typically has a smaller keyboard than a desktop computer, which means less space for keys.

As a result, that row of function keys serve a variety of purposes and to use them as traditional function keys you have to first press the FN key.

How to make Undertale full screen on Windows 10?

Unlike the previous versions of Windows, when your press F4 in Windows 10 it will not take your game full screen. Instead, it opens up the Project screen for you.

So, to get Undertale full screen on Windows 10 you have to use ALT+Enter at the same time to take over the entire screen.

windows 10 project screen
Windows 10 Project screen after pressing F4

Undertale is a video game about a child who falls into an underworld filled with monsters. FIGHT or ACT your way through battles while dodging magic bullet attacks.

Every monster has unique attacks and personality—and they’re all in your way. You can show them MERCY if you want.

You might even make friends. But what will you do if you meet a relentless killer?

Undertale is available in English and Japanese for Windows, Mac, Linux, PS4, Vita, and Switch.


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