Penumbra overture second part

[Thaliur]

How hard it's translate Windows based game to Linux and Mac?

I'm not absolutely certain about this, but as long as there is a compatible compiler available and the game does not depend on Windows/Mac/Linux-only programming interfaces, it should just be a matter of compiler parameters.

But Penumbra seems to use DirectX or OpenGL, not a totally bottom-up-self-written graphics engine (which, as far as I know, no game did since Glide, DirectX and OpenGL).
If it's OpenGL, the interface might be the same in Windows, Linux or Mac environments, but if it uses DirectX expecially the Linux port might prove difficult, since there are about an unreasonabillion different versions of Linux.