The Ultima Underworld demo that was released back in 1992, which covers the entire first level of the Abyss.  This demo was used by Origin Systems to demonstrate their new 3D technology, something almost entirely foreign to PC gamers back in the early 90s.  Copies were available from computer stores and select copies of Ultima VII.  It works beautifully in Dosbox.

Mike Ratzlaff stumbled upon Delver, a first-person roguelike in the style of Minecraft, whilst looking for games for his new Android phone. Finding the game inspirational, he set about attempting to make mods for it, and finally settled on re-making Ultima Underworld. After teaching himself the rudiments of Java in the span of a few weeks and coding tools to help him export graphics from Ultima Underworld, he set about attempting to make his mod, and has evidently been making good progress with it.

This is a multiplayer-enabled Dungeon Keeper level based on the first level of the Great Stygian Abyss for Ultima Underworld. While Dungeon Keeper isn’t able to render sloped surfaces, the layout is otherwise very close to the original.

The map replaces level 61 (multiplayer map 7) in the game, and is for 3 players (but it can be played by one player against the computer). If you need a copy of Dungeon Keeper, you can pick it up for a very reasonable price at Good Old Games.

This is a re-creation of “the entire first floor of Ultima Underworld for Unreal” created by Ryan “Zerker” Armstrong. The level fully supports all of Unreal’s default gaming modes, including co-operative play and botmatches.

It also implements some of the conditions present in the Abyss in Ultima Underworld. Zerker warns: “[d]on’t kill everything you see. Most of the humanoids are in fact, not hostile in this map, to be true to the original. There are still a few hostile Skaarj away from the settlements, but inside the settlements, they’re friendly. The secret door by the silver sapling must be shot to be opened, the one by the fountain of strength only opens from inside, and the one in the Grey Goblin settlement is unopenable. Oh, and if you get sick of trying to jump up the steps in the jumping puzzle, I sympathise with you, but there is some worthwhile stuff up there, if you can spare the minute needed to get it right.”

Naturally, the maps also require Unreal to play. Copies of the game for Windows and Mac can still be found online, though they won’t necessarily be cheap or in stock in large quantities. You can also find the game for direct download on Steam, however, and you can also get it at Good Old Games.

This is a re-creation of the maps of all eight levels of Ultima Underworld for Unreal Tournament, made by Ryan “Zerker” Armstrong. Each map has been “enhanced,” according to the producer, over the original version, so expect your favourite areas from the classic game to have a great new feel to them. All of the maps support the Deathmatch play mode; a few of the maps also support other game modes. (Check the project’s website for a complete listing. And for a pretty concise summary of the game itself and the nuances of every level thereof.)

Of course, the maps also require Unreal Tournament to play. Copies of the game for Windows, Mac, and Linux can still be found online, though they won’t necessarily be cheap or in stock in large quantities. You can also find the game for direct download on Steam, and (for the same price) at Good Old Games.

Note: this is not a complete remake, in that it does not implement the various races or the plot of Ultima Underworld. That said, having a complete set of high quality maps to begin with would serve to cut down on the time it would take to develop a complete remake of the game using the Unreal Tournament engine.

The Abysmal engine is an attempt, by Julien Langer, to create an engine for Ultima Underworld 1 & 2 and System Shock capable of running on modern operating systems, and even on some mobile devices. It will still require the original Ultima Underworld or System Shock data files to run, however.

Abysmal is a successor to previous such attempts at creating an engine for the Underworld games, and builds on the work done by several previous — and now cancelled — projects. It is still at a very early developmental stage, and for a time appeared to have ceased development. However, a cursory browse of its Git repository suggests that Mr. Langer has resumed work on the project as of 2012.

This project, headed up and chiefly developed by Vividos, aimed to re-create an engine for Ultima Underworld game that ran on modern operating systems without the need for patches.

Sadly, as of February 2007, development on Underworld Adventures has stopped. However, the project reached a fairly advanced state before that point, and some may find it worthwhile to take a look at.

A 2D, DOS-based editor for both Ultima Underworld and Ultima Underworld 2, made by Jonathan Rimmer.

The program may require the DPMI Memory Manager because of the Allegro libraries that were used in its making. And, of course, the utility requires the original data files for Ultima Underworld in order to function.

Although Peroxide has ceased to be, some of their old projects are still archived on their site and elsewhere. The Underworld Viewer is a simple utility that renders all the levels of both Ultima Underworld and Ultima Underworld 2 using whichever acceleration mode you prefer so that you can view them and wander through them. It may also be possible to load the level models into a 3D modelling program, if the images on Peroxide’s site are any indication.

And Telemachos, formerly of Peroxide, never seems to run out of ways to keep busy. Building off of the Underworld Viewer, he produced an actual editing kit, the Underworld Game Creation Kit, with which to edit different aspects of Ultima Underworld, as well as walk through all the levels and playtest them.

Both utilities require the original data files for the Underworld games in order to function.

A simple utility for editing character statistics in Ultima Underworld.