To start off with this topic i have some info from uesp.net if you have any specific questions regarding Blacklight
This we know: Blacklight was a major Redoran city on the northwestern coast of Mainland Morrowind close to the border of Skyrim.
To the south are the western highlands and a good road west connects through the Dunmeth pass to Windhelm.
History:
Tiber Septim used Blacklight as a staging ground due to the weak Dunmer defenses here.
Architecture:
Typical Dunmer Craftsmenship with Nord influences
Current events/speculation:
As soon as the Red Mountain blew its top the Argonians of Black Marsh invaded Morrowind beating the vulnerable Dunmer. Most of the Dunmer retreted to Solsthiem.
(The rest of this is all Speculation)
The Dunmer regain their Stength in Solsthiem and a united Morrowind Government Stage an assult on the Argonian held city of Blacklight. They retake the city but suffer major casultys. The Argonians retreat south in the Western Highlands and set up camp there. The Dunmer face new challeges trying to hold the city of Blacklight and also an impending counter attack by the Argonians but they need the help of an outsider to help Blacklights Residents, Economy, Government, and Defenses and Eventually drive the Argonians out of the western highlands.

I might say this could be good, if it were a different Dunmer house to those on Vvardenfell. I don't like to backtrack and we apparently already have one Dunmer city.

It could be different when say more like Solsthiem or Ald'Ruhn in a way or simply have a different building style that would look extremely good

I want this expansion! Seriusly though: That sounds like an awesome setting for a expansion, and give an oppertunity of chosing sides.

I'd buy this never played Morrowind so I'd like to experience the general atmosphere and this sounds like a good way to do that

Sounds great to me!

I would say in this DLC or Expansion you should have the chance to choose sides, lore isnt that much of a factor say you choose the argonian side

They say in order to retake blacklight they need help with things around their camp like food and water, injurys, and quests dealing with events leading up to the big fight over blacklight.
Amount of time this takes could be around a day in real time.

And about the lore, The lore could say this side won mainly because of the outsiders help or this side won because after the outsider left this side over took the other side

Ops, use the terms ignorantly Gonna fix it

Been there, done that. We already have a morrowind influenced city.
High Rock is small, and the perfect size for an expansion.

1. Daggerfall is older than Morrowind
2. Daggerfall had much less technology than morrowind, so you couldn't see high rock in all its glory
3. Much, much fewer people played Daggerfall in comparison to Morrowind
4. We're really only likely to get one expansion. Let's use it wisely. While I'm alll sure we'd love expansions packs to cover all of Nirn, and beyond, we won't get that. The likely one we'll get needs to be prioritized to something better suited.

If it were to be in a neighbouring province, I'd probably choose Dragonstar or Elinhir from Hammerfell.

Why one city?
High rock is comprable size to Skyrim as Shivering Isles was too Cyrodiil.

Because High Rock has a comparable number of cities to 8 Shivering Isles.

Because you cant put the whole province of High Rock into a DLC the Download more than likely wont take it.

True, In all honesty I would prefer OP's idea

I don't understand this attitude of not having anything even remotely related to Morrowind or Oblivion because "we've already been there". Seriously, you can't have House Redoran play a role in an expansion questline simply because they were a faction in Morrowind? ????

Quick we'd better get rid of Daedric, Glass, Ebony armors because we've seen those before, no need to redo them in a different design with better graphics /sarcasm

Personally, I think OP's idea has great potential for a well developed story and questline in a feud between Dunmer and Argonians. I seriously think we'll have something to do with the Morrowind story in Skyrim or an expansion anyway else why would they go to all the effort in the book to change the face of Morrowind?

I'd rather have two big expansions: one in Blacklight area and one in eastern High Rock/Hammerfell, that add lots of new armor/weapon types and questlines, rather than a bunch of little crappy DLC.

I'd also rather have them expand into areas of Tamriel rather than transport you to Oblivion realms.

"High rock is comprable size to Skyrim as Shivering Isles was too Cyrodiil."

It wouldn't be a problem. You'd just need to make the cities smaller, or exclude some of them. A city could easily fall over the 200 years of political upheaval prior to Skyrim.

This expansion sounds amazing. I'd buy it in a heartbeat.
Seriously, too much happened to the Dunmer between IV and V to not be addressed in the games...

I have no problem with having a Dunmer city, that's a nice little nod and could provide both interest and nostalgia. but there's not much point to me visiting places and major aspects like the great houses that we've already seen before, when you can find something new and original. Also, Redoran architecture is boring and ugly.

In summary, don't make it too much like Morrowind because we already played that game?

I'm still in support of High Rock. Morrowind, despite it's age, is still somewhat recent. I would appreciate it a lot more if they would go back to High Rock, make the games come full circle.

Essentially, yes. Too recent, and already featured in a whole city, no need for more. Be more creative.

The problem I have with High Rock, is that it's just too complex. You COULD make all the cities absolutely miniscule little towns and have no other towns for about the same effort as SI, but it just wouldn't feel like they were doing it justice AT ALL to me. It deserves full treatment or no treatment.

A. Blacklight was not in Morrowind the game; even if we went to Vvardenfell it has been destroyed and so would be totally different
B. Blacklight would most likely have much different architecture
C. The situation Morrowind is now in would definitely make the culture and atmosphere totally different, including the Houses/political structure would probably have been destroyed/highly altered. It probably would not be just House Redoran as all Dunmer flee to Solstheim and join together

Basically you're saying "dont make it like Morrowind over again" but noone is suggesting that

A and C are fair enough, but I was under the impression that all Redoran stuff was built mostly the same, as that was something that defined them. I know everything Redoran in Morrowind was the same.

EDIT: But I guess I could see that in the past 140 years the city is rebuilt in a sort of "New Morrowind" style.

You might be able to create magnificence through some mind tricks. Think of Skyrim's map, for instance. It's no bigger than Oblivion's, yet because of the mountains it seems much bigger. High Rock is also a mountainous region, it would also feel bigger. You may be able to squeeze in a few relatively large cities just because they seem pretty spread out. Meanwhile, other cities could just up and vanish, or become smaller properties of larger cities. That's politics, I guess. Wayrest, Daggerfall, and Orsinium come to mind as the three large cities of the region. The rest of them you could probably make into the size of Oblivion's cities, though with some magic, make them feel larger than they really are.

I know, but that actual amount of content juse seems implausible for an expansion. Remember, SI only managed to make 1 city with 23 buildings counting the chapel thing and the palace (about the same as a regular city in OB) and a few small villages. It would appear that making cities is pretty hard. Solstheim was around the same.

EDIT: On a side note (and I promise this didn't affect my thoughts on a High Rock expansion) King Hlaalu Helseth is planning a High Rock mod project (as much of it as can be achieved) and I am involved in settlement design. I designed some architecture and a layout for Orsinium, though I may have made it too big, guess we'll have to see what size the cities are in game to decide, but yeah, it's hell fun.

Even if this isnt seen i still have plans on modding this area all i need is a team more than likely people off this forum.

A. Blacklight was not in Morrowind the game; even if we went to Vvardenfell it has been destroyed and so would be totally different

This is a big issue i had with morrowind it didnt cover all of morrowind and people like me would like to see every inch of Tamriel covered

B. Blacklight would most likely have much different architecture

Every city has different Architecture even Blacklight and as an architectural major it would look very different from ald ruhn