Summary

Rapture Reborn
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My Vision of What a BioShock MMORPG Should be :
Post-BS2, within year or two, a new civilization reasserting itself from the pieces/ruins/chaos.
Not to change too much from what the first two games showed/indicated. Keep the themes along the original game's - the nostalgic aspect with that familiar deteriorated Urban Noir feeling. More filler from that flavoring - a big city built into the size of a town.
* Keeping the mid-1940s (and before) Societal Context - there should be no massive intrusion of Anachronisms.
* No further significant advancements in the story Setting's Technology, and what is there to largely be the 1940s/early 50s 'retro' we saw. The City has been largely in chaos and organized advances would be virtually nil. Few new Plasmids/Tonics, and those mainly the more mundane ones that would have previously existed ( Migraine/Back Ache medicines, Cures for Cancer, Happy Tonics for Depression, etc ... )
* No major outside involvement - No Soviet/KGB invasion, nor CIA, nor Marines shooting the place up with 1960s or 1970s weapons and mindthink. Ryan managed to keep Rapture largely secret. Connections to the outside would be tenuous and with the remains of old associations that intrude briefly.
* Most All the denizens would be Solo game leftovers, no new Big Daddies except maybe 'scrap' Daddies suits with ad hoc repairs made to them. NO NEW Splicer flavors with ad nauseum minor recombinations of existing themes.
References to old characters, some still around (and shown to survive) would have to be done carefully. More showing of the ordinary types who made up the majority of the original population.
The workings of Infinite BS and the Burial at Sea DLC are REJECTED for the most part, as their being significantly contrary and magic-fantasy ( degenerated Infinite BS, stupidity regurgitated badly ).
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MMORPG Would 'Ruin' The BioShock Game ??? ( Become A Too Generic Experience...) 
Not sure how it would ruin anything as you could still play BS1 and BS2 -- as you can now, and you could ignore the MMORPG. I don't think we will get another BioShock Solo game out of Rapture ( ignore the 'Vita' whatever and that Infinite fantasy BS ).
MMORPGs have to have a certain sized following for the game's genre, and since BS1 eventually sold something like 3 million copies that would be a good starting point. I'm not sure what they could do further would do in the same 'Universe' that would add anything interesting ( Infinite BS really IS NOT the same Universe, and what besides Multiplayer Mayhem could THEY really do further in that Lame Fantasyland ? ). You don't want to lose the whole popular Rapture setting, which would be the draw for many Players.
If you read any of these multitude of Wiki postings, the ideas for THIS MMORPG would make it different from the ( generally pathetic ) swarm of others, and be a Proving Ground for the next generation of MMORPG games.
The BS1/BS2 game Assets are just a starting point ( and saves alot of $$$$ which is real important to game companies ) and the game has many more aspects to it than the Solo games. Using the Tools, game mechanics, Modular Design, and Server Systems developed for this game, they could start several others of different genres at a fraction of the current cost ($$$$) that MMORPGs take to develop -- and because they could specialize, they could run them successfully at lower playercounts.
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