Use Ctrl + F to search for the following variables and change their values to match your monitor:
Steam\userdata\[YourUserNumber]\41070\local\SeriousSam3.ini . serious sam 3 cannot set display mode
Download the DirectX End-User Runtimes (June 2010) official installer from Microsoft. Use Ctrl + F to search for the
to force the game into windowed mode, which may allow it to initialize properly. Manual Configuration File Edit Navigate to: ...\Steam\userdata\[YourID]\41070\local\ SeriousSam3.ini in a text editor like Notepad. which is .
Navigate to the Serious Sam 3 app ID folder, which is .