Currently, Portal Knights does not function correctly above 60Hz.  Most graphics card drivers provide a method to restrict the display to 60Hz. If after doing this the game still doesn’t provide valid resolutions in the display settings menu, they can be entered manually in the config file. 

To do this, follow these steps:

  • In Steam, right-click on Portal Knights in the games library 
  • Select Properties
  • In the tab Local Files of the opened window select the option Browse Local Files...
  • The opened Explorer window contains a file called portal_knights.cfg
  • Open using Notepad or your favorite text editor, and the resolution and window type can be entered in this file manually

To play in fullscreen mode, change  "windowType": "Default" to "windowType": "Fullscreen"

To set a resolution (e.g., 1920x1080), change  "windowSizeX": 1280 and "windowSizeY": 720 to "windowSizeX": 1920, and "windowSizeY": 1080