Set Display Mode ((full)): Serious Sam 3 Cannot

Try find on your computer DXSETUP.exe and run it as administrator. If you install it restart the computer and try run game. Steam Community

Steamapps/common/Serious Sam 3/_CommonRedist/DirectX/Jun2010 Find and run DXSETUP.exe as an administrator. Alternatively, download the DirectX End-User Runtime Web Installer directly from Microsoft. 4. Use Compatibility Wrappers (Advanced) serious sam 3 cannot set display mode