drm on linux?

[axiomatic]

Thank you for participating in the Indie Bundle program. I am totally blown away by Penumbra Overture on linux, both the game itself and what a seamless job was done integrating it. For such a complex game, I had no technical problems (apart from the mediocrity of my own graphics card).

I want to buy the Penumbra Collection from the FG store, but I need to know before hand, with absolute certainty, if it has any sort of DRM at all. Unfortunately I wasn't able to find information on this on the site, commerce site, or forums. I apologize if I am being redundant, but please let me know and I'll buy immediately if it is DRM-free like Overture was. Thanks.