[Windows Settings] ➔ [System] ➔ [Display] ➔ [Graphics] │ ▼ [Browse SeriousSam3.exe executable] │ ▼ Select: [High Performance] 5. Validate Integrity of Game Files
What are you running? (Windows 10, Windows 11, or Linux?)
Right-click the file, copy it, and paste it as a backup (e.g., PersistentSymbols_BACKUP.ini ).
If you have a dedicated graphics card but the game insists on using the integrated one, you can force it to use the correct card: serious sam 3 cannot set display mode top
(0 = DirectX 9, 1 = OpenGL)
Look for gfx_bLastGoodFullScreen and change it to . Save the file and start the game. Method 3: Clear and Verify Corrupted Game Files
Run the installer and extract the temporary setup files to a new folder on your desktop. [Windows Settings] ➔ [System] ➔ [Display] ➔ [Graphics]
Navigate to your Steam userdata folder: Steam\userdata\[YourID]\41070\local\ . Open with a text editor like Notepad.
Right-click and open it with a plain text utility like Notepad.
This is the quickest fix. By forcing the game into windowed mode, you bypass the fullscreen handshake that usually triggers the error. Open your . Right-click on Serious Sam 3: BFE and select Properties . In the General tab, find the Launch Options text box. Type in: +fullscreen 0 . If you have a dedicated graphics card but
Windows tries to “optimize” older fullscreen games by overlaying a compatibility layer. This often breaks Serious Sam 3 .
The key takeaway: You cannot fix this from inside the game. You’ll need to edit files manually or use launch parameters.