Those who have two or more monitors may have encountered such a problem that when starting the game, the rest of the monitors turn black.
In this guide, I will tell you how to solve this problem.

1. Download and run DxWnd
   https://sourceforge.net/projects/dxwnd/files/Latest%20build/v2_04_41_build.rar/download
   
2. Click on Edit and Add.
   
3. Set the Path to <path-to-game>\kl2.exe.
   
4. Configure the following options:
   
   • In the Main tab, Position section set your windows size and set Desktop
     
     
   • In the Video tab
     
     • Screen resolution section, set HDMI modes and Initial resolution with your monitor resolution
       
     • Window handling section, set Hide multi-monitor config
     
5. Click on OK, then File and Save.
   
6. Start the game with DxWnd running.

The guide was written using Google translator.
The information is taken from the Internet from various sources.
Verified by me.