Most stressful game?
Probably Dark Souls, there is something about the combat that is punishing yet rewarding. Attacking a boss over and over again until I find it's weakness was infuriating at times. I spent probably 10 hours fighting the fume knight in Dark Souls 2. But that moment when you figure out what the weakness is, or that perfect moment to attack was the best feeling the world, it was that "Ah HA! I got you now!". When you finally beat a boss and that yellow text appears saying "Victory Achieved" it's probably the most relieving feeling ever. You spent the last few hours if not days fighting for that moment.
The feeling of landing a successful parry was amazing as well but so very stressful, it's probably one of the most difficult combat moves to land, and if you time it wrong you're probably going to get smashed in the face with whatever weapon they attack you with. Each weapon has a different "sweet spot" of when to parry. so a landing a successful parry always feels rewarding. But the failure to land it could sometimes result in your death. I spent so many hours trying to figure out where that sweet spot is for enemies, and to this day I still mess it up sometimes.
The addition of invaders is also extremely stressful, the grinds to get from bonfire to bonfire can push you to your limits, and when you get invaded half way there it can be such a defeating feeling. The battles you have with the invaders is the most intense fights you will have. I've had PVP battles last 5 or 10 minutes. The fights you have with other players can be a very intimate experience, and you can really feel the personality of each person when you fight them. Each player seems to have a different style of fighting, you have to learn there strengths and weaknesses just like the bosses.
There is something to be said about the lack of a tutorial though, they tend to just throw you into the game, which for some people is a major turn off. I personally enjoyed the feeling of having to figure out how the world worked and how I was supposed to do things. It was a game that didn't hold your hand all the way through, it was refreshing to find a game that really made you work for things. There is no easy mode, you just have to adapt and overcome each obstacle. I think the lack of any real tutorials or hand holding is what really made me love this game. The world was just there for me to explore and conquer. I have played through the Dark Souls II games about 4 or 5 times. Each play-through felt different and at times, just a stressful as the first time I played it.
Edit: Butterfly of death, never forget..
