What are your steam hardest games ?

try ori and the blind forest one life mode :v

NEO scavenger )

Hitman: Absolution on Purist difficulty (while trying to be as stealthy as possible) was teeth grinding annoying for me.

Last challenges of Cook, Serve, Delicious! Literally impossible even for me.

Darkest Dungeon, not only hard, also a lot of rage.

Super Meatboy.

Metal Gear Rising: Revengeance on higher difficulties. On normal and below, it's not that bad, but on the top couple it's a challenge.

Dark souls is not hard its pretty easy.

Edge
not mirrors edge, the name of the game is EDGE

fun puzzle/timing with a cube, very hard to beat

Oh boy. Oh boy...

MASTER SPY. MASTER SPY

Also:
La-mulana
Bastard's tale
Spelunky
Straimium Immortality

CS:GO

FTL and Super Meat Boy

La-mulana
Giana Sisters: Twisted Dreams
Canyon Capers

Great Permutator

From the ones iny my library I've played so far I'd say Evil Within and Dark Souls.

Genital Jousting. Obviously.

The hardest game I have ever played is wings of Vi. I didn't buy it, I only played a demo and got infuriated, i couldn't even pass the first stage.

Velvet Assassin is way too hard!

Tcheco in the Castle of Lucio (trust me, it IS difficult)

Pretty sure X-COM(or the modern XCOM) is a good way to lose your will to live. But that's turn based strategy, and with only the context of Dark Souls, I don't know if you play that genre or are looking for that type of challenge.

The last boss in YAIBA: NINJA GAIDEN Z is pretty insane on normal, although I played the PS3 version not the Steam version. Not a true Ninja Gaiden game but the only one you can get on Steam AFAIK. Pump the difficulty up and have fun, or at least some pretty twisted and sadistic version of fun.

Salt and Sanctuary

As a funny sidenote, any game that you suck at becomes one of the hardest games you played.