I loved Shadow of Mordor. Really underrated game, and the Nemesis system was a truly unique way to craft memorable moments with characters that were tailor made just to antagonize you.
I had the best Nemesis ever. He was called Zathra of the Spiders. I defeated him so many times, but he would always come back to haunt me. The first time I fought him, he was something of a loudmouth. Just a basic Uruk Captain in Sauron's army with a few hangers on. He'd always flee when low on health, and his gang of followers would mob me when I tried to chase him down, which made him slippery. When I finally "killed" him for the first time, it was by throwing him off of a cliff. Excellent! Finally, he's dead. Right? Wrong. Zathra may be cowardly, but he is resilient too.
A few hours later, he came out of nowhere and attacked me, saying "You thought a little fall like that would kill ME, Gravewalker?!" - I was awestruck. This asshole just wouldn't leave me alone, even after I'd literally chucked him off of a cliff. Once again he attempted to flee after I kicked his ass all over the place - And then I shot him in the head with an arrow as he ran. I thought I had killed him, and that was the end of Zathra of the Spiders. But NOPE. He comes back YET AGAIN, a few hours later -- a newly installed metal plate on his head where my arrow struck him. As our swords clash, he howls something about how whenever his head hurts he remembers how I shot him and that makes him angry. He's now no longer easily damaged by ranged attacks and is a lot tougher.
This whole back and forth with Zathra went on and on for literally hours and hours of gameplay. He'd pop up at the worst possible times, cause me a whole lot of grief and then I would defeat him only for him to flee or for him to "die" in a unique way - Such as savaged by Caragors, thrown into fire, etc. By the end of it, he was a PTSD riddled wreck who was scared of Caragors, Bees, Fire, but became enraged at the sight of me. His in-game biography switched to say that he feared he had become cursed, and the only way to break the curse was to finally take his revenge and kill me. Eventually I cut his head off during a showdown, and I never saw him again. He was gone for good.
And after that, I actually felt kind of... Well, sad. it was such a unique, intense rivalry. Nobody else playing this game would ever experience Zathra of the Spiders, he was unique to my game. His name,appearance, personality and traits were not repeatable. The fact I still think about it now is incredible to be honest.
So, you're god damn right I am excited for a sequel. If it can create a moment half as memorable as Zathra I'm sure it'll be excellent.