I 100% Super Meat Boy back when it was new. I also beat obscure SMB clone Sugar Cube: Bittersweet Factory. That was fun.
I also beat Ghostrunner last year, which is consider hard by some. It was cool game, but I didn't really find it that hard. It was designed more as a puzzle for you to solve, than just mindless action game. It doesn't give you anything for free, you have to learn from your mistakes. So, dying was expected part of the gameplay.
I'm currently playing Dark Souls. So far, I have the same opinion on it as on Ghostrunner. It isn't as hard as internet made me think it was. Speaking of souls-like games, I also beat The Surge 2, but it was so easy that I beat most bosses on the first try.