Dark Souls 3 is getting a DLC-sized prequel courtesy of some talented modders, drawing from all of FromSoftware's catalogue: Bloodborne, Demon's Souls, and even other Dark Souls games. We see this in the mossy-covered old Firelink Shrine, akin to Oolacile's Sanctuary, which has archstones you can use to travel to each location, not unlike Demon's Souls.
There are also cosmic skies and Lovecraftian decor, accompanied by a room eerily similar to Micolash's boss fight—the Bloodborne inspirations speak for themselves.
Dig deeper into the updates and you'll find Heide's Tower of Flame, a Dark Souls 2 location in which we fought the Old Dragonslayer. In this prequel, you find them already dead. There was always a lot of debate as to who this was—an Ornstein imposter, the real Ornstein, or something else entirely.
More recently, it shared a 15 minute gameplay showcase (thanks, PCGamesN) in which we get to see the Rainswept Outpost, Demon Vanguard boss fight—which is essentially the Asylum Demon with its spritual predecessor's name from Demon's Souls—and the Angelic Wall Guardian. They're like if Ludleth was fused with the Winged Knights, two fairly difficult enemies.
Archthrones has been sharing updates for a while now, promising "New Story and NPCs, New Enemies and Bosses, New and Overhauled Levels and Maps, and New and Improved Lighting and Visuals", all completely free. The only catch is that you need a copy of Dark Souls 3 and its DLC, but you can also support the mod page on Patreon.
However, given that it's being developed by hobbyists in their spare time, there's no concrete release date, as anything could change in their personal lives and lead to a delay.
How Dark Souls 2 will factor in remains to be seen, but given that Dark Souls 3 was about the converging of space and time, as everything collapsed in on itself, it makes sense. The first Dark Souls saw a lot of representation throughout 3 with Anor Londo even making a physical return as a main location. The hub is also named after the first Dark Souls'—Firelink Shrine.
Dark Souls 2 saw far less representation throughout 3, but in Archthrones, we'll get to visit Drangleic Castle again in a new light. This towering black fortress was home to Nashandra, the final boss, with a long bridge guarded by giant golems, leading to an enormous door that would only open if fed the souls of enemies. While we've seen Heide's Tower of Flame, Drangleic Castle has yet to be revealed.
Finally, looping back to Demon's Souls, Archthrones is bringing back Stockpile Thomas. This doesn't necessarily mean that its trying to connect every Soulsborne game, as Patches has crossed over from Demon's Souls to Armored Core to Bloodborne to Elden Ring. Now it's Thomas' turn.
The mod is still in development but, after this 15 minute gameplay video was shared, it said, "We're in great need for your financial support! Donations allow us to commission talented artists to work on the mod and thus further refine it for the eventual demo release."