There's no way : Amnesia is better ^^
I really enjoyed Black Plague, the best of the 3 penumbras, far away the two others ^^
But in Amnesia, there's something more, something magic, something very particular that makes the game so immersive and unbelivable in it's atmosphere...
I don't know what it is !
But there is something really incredible about Frictional Games in general.
You know, buying a indie game is not exactly the same thing that buying a 'normal' game.
When you buy an indie game you are thinking that way : "okay I just bought an indie game, let's be sensible ! it's more about original concepts !"
But with Frictional Games, I never thought that way.
I always realised that they were indie games, but everytime played them like they were big games...
And without being decieved.
I think thats why you are incredible, you are really kicking videogame industry's ass !
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best regards