My favorite Skyrim mods are usually ones that alter the flow of the game, or add more character personalizing options. Every time I reinstall Skyrim, Alternate Start—Live Another Life is at the top of the queue. I'm much pickier about quest mods. Adding new story to Skyrim means new writing and voice acting and those are hard things to get right—Enderal managed it, mostly, but it's a rare exception. One of my favorite narrative mods, Sea of Ghosts, gets around the problem by focusing on new locations that are empty, a string of spooky islands.
The Forgotten City, however, does not shy away from new characters. It's a quest mod that adds an entire settlement full of new people, fully voiced, with their own stories all wrapped up in one overarching plot about time travel and human nature and the role of law in shaping a society. It's ambitious is what I'm saying. It even has its own original score.
As for why I'm playing a mod from 2015, a standalone version of The Forgotten City was announced at E3. It'll be a re-imagining, one that takes away all the specifics of the Elder Scrolls universe, changing the characters and the endings but leaving the basics of the structure in place.
I feel pretty confident that having played the mod won't ruin the standalone version, because there's a lot about it that's specific to Skyrim. Once you enter the city (by traveling back in time to a point before its fall), you find that it's divided along familiar lines. The Imperials run things while the Nords do the work, and although there are a couple of non-humans the beast races aren't visible at all. One of the inhabitants turns out to be a member of the Dark Brotherhood, and one's an Imperial soldier who wants to escape so he can get back to fighting Stormcloaks. It's a place entirely cut off from the rest of the country—once you enter it, jumping down a hole in a cave, you can't leave—but everybody's brought their existing prejudices with them.
In spite of all that tension, The Forgotten City should be a place of peace. All the people here, whether they deliberately escaped Skyrim or just blundered down the hole, are under the jurisdiction of the "Dwarves' Law". This place was built by the Dwemer, and they left behind a safeguard for anyone who took up residence after them. If anyone in the settlement sins, the whole population will be punished for it. Fatally.
Having seen the city's future, you know that's about to happen. Something's going to set off the magical punishment left behind by the dwarves and you've only got a limited time to figure out what it was and prevent that from happening. Fortunately, you can make multiple attempts. If you fail you can go back to the moment of your arrival, starting another time loop armed with everything you've learned. There's even new dialogue to take this into account, including some funny stuff when you try to convince someone you know what they're going to say next.
As well as getting to know the people, you get to know the location as well. It doesn't seem huge at first. There's a palace, a single district and a lakehouse, but there are other places to unlock and secrets to find. The limits to the area mean that you learn your way around properly, and eventually figure out where everybody lives and how to navigate it at speed. It's the characters I keep thinking about, though. The two researchers happy to have this opportunity to dive into understanding the Dwemer, even if they can't share what they learn. The paranoiac who correctly believes they're all in danger, but responds to it by wandering around with an axe like a maniac. The self-declared jarl who sounds like someone doing an impersonation of Patrick Stewart, and the merchant who swears he's honest, and the cynical healer who hates being stuck in the Forgotten City but says it "Could be worse, though. You could be living in bloody Skyrim."
It's maybe a bit ridiculous that all these people got here by just jumping down a hole (OK, one of them was pushed), but having them stuck together in one place where they all know each other makes for much more interesting interactions. The Forgotten City feels like an argument in favor of constrained locations, for how great open-world games can be when they focus on depth rather than width. And that's why I'm looking forward to the game it eventually becomes, once it cuts the ties to Skyrim and transforms into something new.