If you have a triple-monitor gaming setup, disable the surround/eyefinity group temporarily. Serious Sam does not natively support ultrawide or multi-monitor spanning in older versions and will crash on init.
These versions often fail when the initial configuration file is corrupted or points to an unsupported mode. Reset the Configuration Serious Sam Cannot Set Display Mode
"C:\Games\SeriousSam\Bin\Sam.exe" +safe 1 +fullscreen 0 If you have a triple-monitor gaming setup, disable