I seriously recommend checking out Celeste if you're into platformers with the difficulty of dark souls. The main game is completable in 8-10 hours, but theres about 2-3 times more content in that game. There is also a speedrunning and a modding community.
I've heard so much about Celeste and have never gotten around to checking it out, so I was really pleased to see it coming to Gamepass, I'm going to have to try it.
Something about Celeste is truly rewarding. You're very right about the challenge being fair, and I think that's what does it. It's definitely tough, but not unreasonably so. It's so worth it.
Edit: replied to the wrong comment, but my point still stands haha
It's hard but the levels are one screen long and you restart instantly on death (or after pressing a button). So you don't have to replay lots of stuff and you don't lose any progress. I don't like Dark Souls but I loved Celeste.
Starfield and Forza Motorsport are coming to Game Pass on day 1. Both pretty solid reasons to stick around (or at least resub in a month or two) IMHO.
But the real trick is to keep an eye on Slickdeals. I got three years of Game Pass Ultimate for like $120 or something like that a little while back. Game Pass is so much better when it's a fraction of the normal price! 🙃