It wouldn’t be a top 10 hardest games without Dark Souls. Although it’s probably not the hardest one out there, this one was actually marketed for its difficulty, hard bosses, and the fact that you are going to die a lot.
There is no doubt that everything in this game wants to kill you, but when you learn from your past mistakes and manage to defeat the enemy your heart will be overcome with joy. In battles you will have to think tactically about the right time to strike and the right time to defend or dodge, as even the trash mobs can kill you with very few hits. Although Dark Souls is difficult and punishing, it is also fair.