It Would Work

[Thaliur]

I'd definitely watch a Penumbra movie if there was one. But I think there is too little dialogue in the game to just transfer it on the "big screen". A lot of the story details would have to be changed.
Also, games live from interactivity, and what feels awesome in a game might be just boring in a movie, but I think if the storyline was adapted for movie use, it would work.