How crucial is it to follow the story line?

[darkely]

Oh man, why would you skip Overture, the best of the Penumbra series?
Overture is the best game of all from Frictional Games, even better than Amnesia.
You have a very oppressive atmosphere in the mine shafts and so incredible physic puzzles!!!
Don't skip Overture, otherwise you will missed most content.
Black Plague isn't an improvement for me, it is little scarier, yes, but the core game isn't such immersing like Overture. Less puzzles and a strange story that plays in minds and felt implausible some times.
Trust me, Overture would be the best experience!

I know that the game ends odd I cannot find the ending any where *sobs* but I am trying to beat this game it is kind of annoying me now D:<