A DRM-free version is often available on GOG for those who prefer permanent ownership without a launcher.
You can find the Serious Sam Classic: The First Encounter on Steam . A DRM-free version is often available on GOG
Review: “Serious Sam: The First Encounter” (Computer Game) Windows XP, Vista, or newer
One of the best parts of this classic is its accessibility; it can run smoothly on almost any modern laptop or older desktop. Windows XP, Vista, or newer. Processor: 1 GHz. Memory: 256 MB RAM. Graphics: DirectX 7 compatible 3D graphics card. Graphics: DirectX 7 compatible 3D graphics card
While the game has been offered for free during limited-time promotions on platforms like GOG.com , it is generally available as a paid full version on major digital storefronts:
Serious Sam: The First Encounter — A Relentless Throwback to Classic FPS Action
Some legacy versions and demos are preserved on the Internet Archive for historical access. Modern Enhancements