Hard Video Games

What are some good hard games beside the obvious Dark Souls and Super Meat Boy? I love me some hard shit.

Quake.

@uninspiredcup: Quake isn't hard, I beat it when I was like 5 years old. I really don't think there are many hard first person shooters. I can't think of any other than some parts of Wolfenstein.

FEAR on harder difficulty is a challenge.

Yes.

I broke my controller because of Dark Souls. :P

Hard Reset on Insane

Bit of a different approach: Total War Attila i'm finding to be a pretty stiff challenge.