Serious Sam Public Demo 2

I don't know but you can win some serious sam here!

maybe a beta test from taketwo for their next project perhaps? I have not even redeemed my bundle but there's sth abt the purchases will partially go to a new serious sam title coming soon

You can read the info on the Humble Weekly Sale page.

Basically, its the open beta that was originally released as a demo while 'The First Encounter' was being developed.