The most reliable way to acquire the classic version is through digital storefronts that offer modern compatibility fixes:
: Open-source versions and modern patches like the Serious Sam Classics Patch on GitHub allow the game to run on Linux, macOS, and at 4K resolutions. System Requirements Download Serious Sam Classic: The First Encount...
: Available as Serious Sam Classic: The First Encounter , often bundled with later entries or provided for free to owners of the HD remake. The most reliable way to acquire the classic