Unheard of penumbra game

[Googolplex]

Let me explain what the game is.
The free tech demo of Penumbra was just a school project by Frictional Games and they won a student developer competition. This game is no part of the Penumbra series, it's just a tech demo shows the engine, how gameplay and physics working etc. Later they got a publisher for the "true" Penumbra series with full-length story.

The tech demo is not a classical demo with limited content, it's full playable, has same core story like Overture, but is a completely different game.