So, I listed EVERYTHING we know about the game

SpoilerDiscussion & Info

And here it is (again! We're no longer [deleted]). Sources linked at the end. If a point doesn't reference a source it's because it's a commonly-enough known information. Some of the sources mention things officialy confirmed in a different source that I couldn't find. I would appreciate any help in finding those if there are any inconsistencies. The points aren't organized in any importance order, just by the theme of them. From is short of FromSoftware.

THINGS OFFICIALLY CONFIRMED

OVERALL AND DEVELOPMENT INFORMATION

The game was announced on June 9th, on E3 2019' Xbox presentation. The announcement was done through a CGI trailer.^([53])
Developed by FromSoftware (duh)
Published by BANDAI NAMCO Entertainment Inc.
The in-game world's history and mythos were crafted by the one and only Hidetaka Miyazaki, in collaboration with George R.R. Martin
Main story by Miyazaki and lore/mythology from Martin^([5])
Miyazaki compares the mythology that Martin wrote for Elden Ring to that of the dungeon master’s handbook in a tabletop RPG^([5])
George Martin's part in the game is already finished^([1,5])
As of June 9th 2019 the game still had a load of work ahead of it^([3])
FromSoftware's largest game to-date
The game is expected to launch for PS4, Xbox One and PC
Development started just after development for the Dark Souls 3 DLC had ended^([3])
At the time^ planned as a more classic fantasy title compared to other currently in early-development or still being considered games^([3])
From wanted to implement things that they weren’t able to do in the Dark Souls series^([3])
Process of development same as Sekiro. While assigning co-directors to each project, Miyazaki took direction over the various game design, art and musical aspects of the titles^([3])
As of April 14th 2020, FromSoftware were developing the game from home^([42])
From didn't want to create a more linear or storydriven experience.^([5])
Yuka Kitamura, who worked on all previous soulsborne titles' soundtracks, is working on Elden Ring's soundtrack as well^([32])
There IS more info coming^([3])
Elden Ring's original trailer was supposed to be shown at the Taipei Game Show in february, though it'd be china-localized. The event got postponed to June thanks to coronavirus^([43,44])
A short video with a song, presumably a shortened version of a piece from the OST and maybe the opening cinematic, was posted on the official twitter acc.^([45])
Phil Spencer Has Played "Quite A Bit" Of Elden Ring, Calls It Miyazaki's "Most Ambitious Game".^([47])
The game is, officialy, still in development as of 31st October 2020, and FromSoftware appreciates our enthusiasm for it (yay).^([54])
On December 30th, From's Promotion, Marketing and Communication man Yasuhiro Kitao posted a tweet, thanking the community for deciding ER as TGA's most anticipated game. In that same tweet he also stated that "By virtue of those who play our games and continue to hold us to a high standard, we can forge ahead with development undaunted and highly motivated. (...) It seems the world might not be mended for a while yet (...) see you in 2021.^([60])
On December 31st, FromSoftware made a tweet wishing everyone a happy New Year, also stating they can't wait to "work with us again next year" (google translate).^([61])
Soon after, on January 1st they once again confirmed Elden Ring is still in development^([66])
On January 8th, the company Digic Pictures released their version of the Elden Ring trailer. The company, as I understand it, has created the E3 2019 trailer, or at the least helped with it's creation. The trailer reuses visuals, but a new piece plays in the background, presumably from the game's soundtrack. Additionaly, as the credits roll we can hear a fragment of the original trailer's song.^([70])
Frognation and Ryan Morris, who worked on localizing all of Miyazaki's games since Demon's Souls except Sekiro, are back handling the localization for Elden Ring^([71])
Ultra HD won't be available on Xbox One or Xbox One S consoles.^([2])
HDR functionality will be available with supported games and TVs.^([2])
Enhanced features for Xbox One X are subject to release of a content update.^([2])

GAMEPLAY

It's a third-person action-RPG, epic- and dark-fantasy medieval title, though it is more than just that^([3,22])
Although it puts more focus on RPG aspects, responsive melee-based combat will be present^([3])
Gameplay-wise, it’s heavily based on Dark Souls, and ER could be titled as it's natural evolution. That doesn’t mean that the gameplay will be identical, but you could say that Elden Ring belongs to the same genre^([5,6])
The more extensive world will form the base of Elden Ring’s gameplay, and its mechanics are designed with that type of environment in mind. With a more open and vast environment, the way combat plays out becomes fundamentally different^([5,6])
The main character will be able to traverse the world on a horse, with the ability to fight enemies while mounted^([5])
Will include a wide variety of weapons, magic, and ways to engage enemies^([3])
More variety in the ways for players to overcome challenges and tweak their tactics when facing enemies compared to the Dark Souls series^([3])
It will contain character customization elements^([3])
The game is open world, or rather it has a large, open field to play in^([3])
With a larger world it became necessary to implement new systems and action mechanics^([5])
In this danger-filled field you will find many areas ripe for exploration, as well as intricately designed, multi-layered castles and such^([3])
Will contain boss fights^([3])
Villages will be the dark dungeon-like ruins that you have come to expect from From^([5])

LORE

While studying various open-world games, Miyazaki refrained from being too heavily inspired by them, and rather chose to focus on making an experience only FromSoftware could deliver^([5])
Elden Ring isn’t about a ring you wear on your finger, but that “ring” is used in the context of “circle"^([7])
In-game, Elden Ring is the name given to a mysterious concept that defines the world itself. It's a mysterious, key element in the foundation of the game's world. It forms the rules and rhythm of it^([3,6])
This^ Elden Ring has been shattered. The significance of this will be one of the important themes of the game^([3])
Instead of creating Elden Ring’s main story, Martin wrote about a time long before the era the player actually explores^([5])
The period the player actually explores is still connected to the old times, so as you slowly discover why the world has become the way it is, you will learn more about Martin’s mythology^([5])
We'll uncover the game's lore through exploration and fragments of environmental storytelling^([5])
Regarding the concept art^([4]), the character on it portrays the darkness that the world and story possess and the will, or ambition of mankind^([3])
Elden Ring’s NPC characters are more compelling than in Miyazaki's previous works^([5])
For Elden Ring Miyazaki is going back to his Western fantasy roots^([5])
The game’s themes are very different from From's previous works^([5])
It's a very painful fantasy drama. There's pain there and from a human perspective there are themes of racism, politics, citizenship and so on.^([46])*
It's a work that's psychologically quite painful in a lot of ways^([46])*
The actions of the characters really make you think "yeah, humans are like that".^([46])*

*Note, this information is based on a user's translation of an offial interview. I've recieved info about these points possibly being about ASoIaF instead of ER, but I can't read Japanese so I can't confirm nor deny anything.

THINGS STATED BY A CERTAIN ResetERA USER AND VARIOUS LEAKS AND RUMORS

Omn*******/Deleted Member 2229 was a user verified by the ResetEra forum's admins to be a FromSoftware/Bamco insider, though I don't know to what extent, because it'd be dangerous for him to reveal it to the public. He has previously accurately leaked things about Sekiro (for example it's subtitle Shadows Die Twice) and has hinted about the Demon's Souls Remake. It's your choice if you want to believe him or not, this is still officially-unverified information that might ruin/spoil things for you or might not turn out to be true. Objectively those points are worth listing. I might not have gotten everything because ResetEra is a pain to navigate without an account so I might not have found all of Omni's posts and I don't have access to their discord server. I noted as much as I could find (except the IGN JPN interview because I can't read Japanese) and again I would greatly appreciate letting me know about any information contained in the sources that I missed.

edit: For Great Rune-related info, please refer to this great post made by u/bioeng_

OPEN WORLD & WORLD IN-GENERAL INFORMATION

The biggest single change in terms of design moving from Dark Souls to Elden Ring is the open world^([9])
This is easily From’s most immersive world yet filled to the brim with secrets and stuff From has never done before in multiple areas^([8])
Interconnected design is larger and deeper than ever^([8])
You'll be able to see an area long before you reach it (sometimes you can go straight to it), as well as look back across the land to places you have already been, seeing how places connect and what not^([9,11])
The game's world is quite large^([9])
One of the pillars of design in Elden Ring is to create a meaningful and fully realized world^([9])
The world will feel real and alive, on a much greater scale than in previous titles^([9])
The world will contain interesting landmarks to draw your attention and help you familiarize with your surroundings. They'll also act as points of interest along your journey from one goal to another^([9])
Areas will connect to one another like in Dark Souls 1^([9])
The landmass will be similar to the works of Fumito Ueda (Shadow of The Collosus) - specifically the vastness, the openness, the freedom and the clever funneling of player pathing, but less so the emptiness and the lack of player freedom or player choice^([9,11])
It^ will contain degrees of verticality as well as natural transitions between the more open sections and the less open sections^([9])
The landscapes of Scotland served as an inspiration for Elden Ring’s landscapes^([9,49])
The player will be able to affect and change things in the world, but the world will also change on its own^([9])
There will be plenty of meticulously crafted areas too^([9])
More open level layout^([10])
No BOTW style exploration^([11,37])
Dynamic day/night & weather, lighting, wildlife, dynamic enemy placement, roaming enemies and large roaming creatures to be present^([10,11])
Different races of folk will inhabit the world, some of which already explored in past games but done differently this time. Some races are present in the trailer^([13])
The scope of the world, lore and narrative is more grandiose than past games^([13])
The game won't take place in just a single land like past titles, but multiple - with their own distinct qualities, characteristics, visuals and recognizable inhabitants^([13])
There are wolves and dragons^([11,14])

OVERALL AND DEVELOPMENT INFORMATION

(regarding news) This journey doesn’t end with E3, this is only the beginning^([8,34])
Elden Ring is sort of a new start for the Souls games^([10])
It's not Norse-based^([12,49])
The jump from Dark Souls to Elden Ring is not as big of a jump as from Kings Field to Demon's Souls but as a whole, a bigger jump than Demon's Souls to Dark Souls^([17])
When writting his posts, Omn******* toned stuff down rather than playing it up so that things didn't sound hyperbolic^([21])
Elden Ring is expected to contain esoteric wierd shit^([23])
From is prioritizing interesting and engaging game design over raw graphical prowess. Just like in their previous games^([25])
Elden Ring is the culmination of a decade of iteration that started with Demon's Souls^([25])
From is unlikely to switch to using Unreal Engine 4/5 any time soon^([27])
The game is targeting and being developed for current gen consoles^([29])
The game has been in development for years for current hardware^([30])
With backwards compatibility on both consoles the game will undoubtedly benefit from things like faster/instantaneous loading and higher frame rates^([31])
Elden Ring isn't the last ARPG From will ever make^([31])

edit: included the "delay" / silence information

Things were meant to happen, but they didn't. Sometimes you need to keep your plans fluid and change things along the way because it's ultimately better for your product^([15])
It's not because of Phil Spencer or Microsoft^([15])
It has nothing to do with GRRM or development issues. The game is fine^([16])
From/Bandai decided to not show it for valid and "mundane" reasons, meaning there's no secrets or conspiracies worth speculating about^([16,41])
It's not the only Bandai game in this situation. There are reasons outside of From's or Bandai's control for that that involve the realities of doing business^([16])
COVID-19 has also affected many things^([16])
The infamous trademark issue regarding EldenTec is not relevant^([18])
Stuff was planned and it fell through, and coronavirus just made that situation worse^([19])
As of May 23rd 2020 FromSoftware was in work-from-home mode due to covid. Supposedly they were to remain so until the end of said May^([20])
The game isn't in any kind of development hell^([24,40])
The silence is not a way to make sure Demon's Souls spotlight isn't stolen^([26])
Development has still been progressing at a reasonable pace all things considered. There was no reason to worry about the game^([28,41])
As for marketing, "they're working on it, they've been working on it, shit happens"^([28])
Back in June the belief was that we wouldn't need to wait a particularly long time to see more news^([35])
Jason Schreier has stated that originally, Elden Ring was supposed to release in the 1st half of 2020^([33])
If IGN Middle East is to be believed, ER was supposed to appear at TGA 2019 with an early 2020 release date.^([48])
0mni also confirmed ER at TGA 2019 was supposed to happen. It didn't because From wanted to present their game in it's best light. ER was then supposed to appear at another event, but covid happened^([50])
Back in December we could find Elden Ring featured on Benjamin Roach's artstation profile as a 2020 product. More info on Benjamin's legitimacy in the source.^([52])
Back in June 2020, Imran Khan has stated that Elden Ring's gameplay might not be dropping in 2020 at all.^([55,56])
In August 2020, Jeffrey Grubb stated that "he doesn't think we'll get Elden Ring news this year with the possible exception of The Game Awards".^([57])
Imran Khan, who previously stated we shouldn't expect to see Elden Ring in 2020 at all, has stated that "there are some reasonable hints that an Elden Ring trailer is coming soon" and that he "wouldn't be shocked to see a trailer next week." (he was talking about TGA).^([58])
Lance McDonald stated that it seems to him like Elden Ring was ready to be showcased publicly as of Dec 3rd, 2020. "It seems like there's some people working on ER who they only bring in when the games are nearly finished"^([59])
Jeff Grubb gave us information about the next game's trailer date on a GB Decides podcast on December 11th. He mentioned how his back-and-forth on whether the game's gonna appear on TGA made us (r/eldenring) complete lose our minds, which is obviously fake news. More importantly, regarding when the next trailer shows up, he stated we only need a little bit more patience. Not as soon as a few days or weeks away, but it won't be "months and months and months" before we'd see it. "They're obviously working on this game. (...) They didn't show it here [TGA], I think they probaly could have if they wanted to, I think it's at that state. Let's give it a month or two more."^([64,65])
On December 28th, a conversation between an Italian journalist and a streamer, if believed, cast some light on ER's development. Everyeye.it's Head Redactor had this to say about ER: "If there wasn't Covid, you would be already playing it (...) for a while." When asked about development issues, he stated the problem was not the development phase but the polishing phase. He also reinforced the fact that, as officialy stated, ER is similiar to the Dark Souls series' games. He also confirmed the project was called "Great Rune" in early development.^([63])
On January 8th, 2021 Jeff Grubb stated that "By March [2021] I think we should hear something about Elden Ring".^([67])

GAMEPLAY INFORMATION

Changes and improvements to AI and design with new ways to trick the player into a false sense of security before being murdered^([9])
Effort is being put into improving both magic and melee combat and movement, some QoL things coming for those systems^([10])
Stat allocation, the biggest gear variety yet,Fashion Souls, build variety present^([10,12])
Dedicated jump button, no mario-esque hopping on heads though^([10])
No Sekiro combat depth, too complicated with build variety (as in different weapons and magic)^([11])
PvP and Coop confirmed ^([12,38,39])

LORE AND STORY INFORMATION

The player character will just be a human or a not-human(human-like), while important inhabitants and enemies will be a part of different races, some of which inspired, some original.^([13])
Important magic wielders will be more fleshed out than usual, both in terms of their sub-narrative as well as organizations of their own^([13])
Schools of Magic aren’t just about what sort of element you wield but which school matches the ideals you most closely adhere to and which organization you might feel more connected to^([13])
In-game, the Elden Ring was like the state of the world, comparable to Earth's Moon or atmosphere^([13])
After it^ shattered, all the worst and unimaginable things it was keeping out start to make their way in, someone you once knew becomes something and existence itself and everything within and around it just stops working as intended. And you get to witness the results of that^([13])
Governing bodies, nations, gods and demigods to be relevant^([13])
It will contain a lot more characters with stories that will span further across the game in terms of location and story progression with their own motives and personal ambitions. Like the larger and more involved NPC quests of DS3 but on a more consistent scale^([13])
The player will have a more interesting and involved personal narrative^([13])
A powerful narrative with more dramatic weight than preceding titles^([13])
What GRRM wrote for the game is essentialy a short story^([36])
A Chinese content creator Longqi Bangbangtang leaked info about the game around 30th of December. Most noticeably Longqi showcased two concept arts of in-game characters (no info on whether they're bosses or NPCs or whatever), one of which is most likely the Tusked Giant we see in the trailer.^([62])
On January 15th, 2021 a bunch of concept art created by Gabriel Björk Stiernström for the E3 2019 trailer got publicly released. The images depict the old man and the woman, hammering down on whatever they were hammering down on in the trailer, from many angles, also revealing details about their surroundings in the scene. The pictures are also commented on by the author, both on the ArtStation page and in a comment he made on this sub, both are definitely worth checking out.^([68,69])

edit: he has since deleted everything, though luckily I've archived all the pictures and the comment should still be there.

And that would be it. I'll update the post once something new / something I may have missed comes up. Now, let's wait for the ~~Xbox July event~~ ~~gamescom~~ ~~Game Awards~~ ~~Taipei Game Show~~ E3 Bandai Next to confirm all of that. Right?

Sources:

note: Omn******* has since deleted his account and his name was changed to Deleted Member 2229.

^([1])https://en.bandainamcoent.eu/elden-ring/elden-ring

^([2])https://www.xbox.com/en-US/games/elden-ring/

^([3])https://news.xbox.com/en-us/2019/06/09/hidetaka-miyazaki-and-george-rr-martin-present-elden-ring/

^([4])https://www.instagram.com/p/ByiW7PUAgMX/

^([5])https://www.ign.com/articles/2019/06/21/elden-ring-is-an-evolution-of-dark-souls-says-creator-a-e3-2019?sf104471595=1

^([6])https://www.ign.com/articles/2019/06/11/dark-souls-and-bloodborne-creator-says-elden-ring-is-a-vast-open-world-souls-like-game-a-e3-2019

^([7])https://www.ign.com/articles/2019/06/12/elden-ring-fromsoftware-explains-the-meaning-behind-the-name-a-e3-2019

^([8])https://www.resetera.com/threads/what-are-you-expecting-to-see-from-fromsoftware-this-year.115159/page-34#post-21284690

^([9])https://www.resetera.com/threads/from-software-development-speculation-everything-we-know-about-their-current-projects.163312/page-8#post-28112018

^([10])https://www.resetera.com/threads/from-software-development-speculation-everything-we-know-about-their-current-projects.163312/page-32#post-29488928