Penumbra is real - possible inspirations?

[Deep One]

Oh man, why are the best games only HL2 mods?
I don't have HL2 (shooters makes me ill) and I do not want steam (DRM makes me more ill).
There's a standalone version of this great looking game?
Thanks Deep One, anyway.

You can play it for free, just download Steam and install Source SDK. Don't be so critical, you don't have to buy anything Steam isn't going to sell your PC specs to North-Korea.