Official specs from Steam

Serious Sam: The Second Encounter system requirements

Minimum and recommended PC specs as listed by the developer on Steam.

Minimum

OS *Windows 95 OSR2, Windows 98, Windows 98SE, Windows ME, Windows NT 4.0 (with Service Pack 5), Windows 2000, Windows XP, Windows Vista or Windows 7 operating system
ProcessorAMD K6-3 400MHz, Pentium II or Celeron-A 300MHz
Memory64MB
Graphicsfull OpenGL compliant 3D accelerator
Hard Drive450MB free hard disk space
Sound100% Windows compatible sound card

Recommended

ProcessorAMD Athlon 650MHz or Pentium III 650MHz range processor
Memory128MB
GraphicsnVidia GeForce256 or TNT2 ultra, PowerVR Kyro, S3 Savage2000, 3Dfx Voodoo3, ATI Rage128 pro
Hard Drive550MB free hard disk space
SoundCreative Labs SoundBlaster Live

FAQ

What graphics card do I need for Serious Sam: The Second Encounter?

Minimum: full OpenGL compliant 3D accelerator. Recommended: nVidia GeForce256 or TNT2 ultra, PowerVR Kyro, S3 Savage2000, 3Dfx Voodoo3, ATI Rage128 pro.

How much RAM does Serious Sam: The Second Encounter need?

Serious Sam: The Second Encounter needs 64MB at minimum, 128MB recommended.

How big is Serious Sam: The Second Encounter?

Serious Sam: The Second Encounter requires 450MB free hard disk space.

Does Serious Sam: The Second Encounter run on Mac or Steam Deck/Linux?

There is no native macOS version. There is no native Linux build (Proton compatibility may vary).