When the game's good enough, the mod scene lives eternal, and there may be no better proof of that than Quake. The most ambitious Quake map ever completed was uploaded on Quake mod site Quaddicted in June, and it looks unbelievable for a game that's now more than 20 years old. Called The Forgotten Sepulcher, the map is a modern reinterpretation of the original Quake map E1M3: The Necropolis.

Quake remembered When Quake turned 20, we looked back on its legacy and how it came to be. Check out our retrospective for a little 90s idstalgia.

Built by two Quake level designers, Simon "Sock" O'Callaghan and Henrik "Giftmacher" Oresten, The Forgotten Sepulcher is a stunningly intricate and densely interconnected map that pushes Quake far beyond its natural limits. As the download page notes: "This release exceeds several limits and the only engines currently capable of running it are specially modified versions of Quakespasm and Quakespasm-spike."

Put it this way: while the original E1M3 is made up of around 1,000 brushes, which is the term for each individual shaped block that makes up a map, The Forgotten Sepulcher features 60,000. Thanks to id releasing Quake's source code online, modern updates to the engine have been able to push it further and further, doing things that would've been impossible in 1996.

But the Forgotten Sepulcher isn't just detailed—it's also huge compared to most Quake maps. There are 297 monsters to defeat and sub-bosses, if you can find the keys to their locked doors. Nearly 90 secrets are tucked away waiting to be uncovered. There's a multitude of destructive objects. Enemies burst from doorways. Also, there are fishing ogres.

Just an ogre, fishin'.

It was initially designed by Oresten, a teacher from Sweden, who'd been following Simon O'Callaghan's work on creating a campaign and mod for Quake called Arcane Dimensions, and decided to make a level for it himself.

"My intention with the map was to rehash the original E1M3, a swampy green-brick monster," Oresten says. But he wanted to build on it, taking advantage of Arcane Dimensions' additional monsters and weapons, tools and engine tweaks.

"I really liked the organic look and feel of the original map Henrik made and asked him to join the team," O'Callaghan, who has worked on level design for Wolfenstein: Enemy Territory and Crysis: Warhead, tells me. "We then worked together over last summer and developed the map further."

The main route winds around and through towering cathedrals, climbing to upper levels and crossing areas you've been through before, and then descends into broken chapels and flooded catacombs. Along the way, you'll open up shortcuts to previous areas, giving The Forgotten Sepulcher the feel of some kind of super-compressed Dark Souls. It's always a good idea to examine the environments for broken doors you can blow open and for places you can jump up broken masonry to reach walkways above.

In other words, it feels modern, even though it's written in Quake's super-blocky and monumental level architecture.

O'Callaghan and Oresten subdivided the first draft of the map into primary and secondary routes. You can access many areas in several different ways, often by climbing, but the primary route is lit with torches to make it visually obvious.

There are also all the little touches that remind you of its source material. There's explicit stuff, like the room early in E1M3 where there's an ogre behind bars, shooting grenades at you, and stairs that go down to the right and a great doorway to the left. This level is emblazoned on my memory from when it played at 15fps on my 486-66, but I'd forgotten how interconnected it is, just as The Forgotten Sepulcher is, too. E1M3 only had 47 monsters, though.

"I think a lot of the Quake style in [The Forgotten Sepulcher] comes from the consistent architecture and artwork," says O'Callaghan. "I really tried to keep the palette consistent and try to show progression with architecture. Like the place has been built over time and they re-used and upgraded things."

The classic E1M3.

Look across the stonework of the opening space and you can see layers of geometry that show how it's been crumbling away. The harsh angles and lighting that Quake imposes make for powerful silhouettes. "Quake is very brutal with shapes, so the architecture has to look strong and stable, like it's stood the test of time."

The Forgotten Sepulcher is the newest addition to Arcane Dimensions, which is both a campaign of maps designed by various different Quake map designers and also a set of functional tweaks and features that are focused on making it easier to build complex maps.

A couple of months before release, though, The Forgotten Sepulcher hit even the limits of Arcane Dimensions and QuakeSpasm, the modern Quake engine on which it runs. Its 60,000 brushes are way in excess of even contemporary maps, which are usually 4,000-5,000.

Enter a third member of the team, Eric Wasylishen, who massively optimised the compiling process by transforming hand-placed elements such as vines and corpses into special entities to reduce the load on the engine, as well as shortening compiling into minutes, rather than the days to weeks that it used to take.

"Ha, there were horror stories of maps in the late 2000s and early 2010s when they were taking a month to compile," Wasylishen says. O'Callaghan says that his work on the compiler, which has allowed designers to design and playtest a lot more fluidly, has given new life to Quake's mapping community.

And the detail and scale it's lent to The Forgotten Sepulcher makes it a real joy to explore, and a perfect place to be reminded of Quake's super-smooth feel. The gib noises are perfect, even 20 years later.

Installation is fairly straightforward if you own Quake:

Download a specially adapted version Quakespasm and drop its files into your main Quake directory.

Make an "AD" folder in your Quake folder and drop Arcane Dimension's files into it.

Download ad_sepulcher and drop its files into your AD folder.

Run it from the Quakespasm shortcut, go to MODS in the main menu and navigate to the AD folder, and you're in Arcane Dimension.

To go directly to The Forgotten Sepulcher, take the portal to the left of where you start into the second level hub, and then it's directly to your right.