Is Sekiro the hardest game ever?

I've been hearing a lot of buzz about Sekiro: Shadows Die Twice, and I'm curious if it's really as challenging as some people claim. Have you had a chance to play it yourself? If so, would you say it's the hardest game you've ever played, or does it just have a reputation for being difficult? I'm interested in hearing your thoughts on the game's mechanics, boss fights, and overall difficulty level.