Fullscreen Mode on Windows 10

If you're facing this exact problem, you've come to the right place! Upon researching online on the different solutions to solve this issue, I've devised two methods you could use: Alt + Enter and Override High DPI Scaling Behavior.

From the two, this is a temporary solution. You'll have to do this every time you launch the game.

Press Alt + Enter once. If you notice, this launches the game into window mode. You may have to click the in-game screen in order for this to properly work. Press Alt + Enter again. Hooray! It's in fullscreen!

This is a more permanent solution to keep the game in fullscreen whenever you decide to launch it.

Open This PC.
Select whichever drive you've installed Steam on. It will most likely be in Windows (C:) drive for you. As for me, I've installed it on an external hard-drive. Follow this path. Select the game's application file as shown.
Right-click and select Properties. Select the Compatibility tab.
Then, select Change high DPI settings under Settings. This will open another window.
Finally, tick the Override high DPI scaling behavior under High DPI scaling override. Close all windows and restart Steam. Launch the game and watch the magic!
Hooray! It's in fullscreen!

I hope this guide helped you out somehow! If there are any other methods out there to solve this issue, please do let me know. It'd be awesome to have more people play this under-rated game and it'll surely be a bummer if their first impression is spoiled because of this.

If you're still having trouble following the steps, don't be afraid to leave a comment! I'll be more than happy to help. I can even record a YouTube video demonstrating the two methods if it's highly requested.

Don't forget to rate and favourite!
Not only will I highly appreciate it but it'll also be a way of reaching out to other potential players facing this exact issue.