The Lost Vale was planned to be an add-on for Ultima 8, but it was never released. Sources seem to suggest that the add-on was fully made and ready for release, but was not released because of Ultima 8's relatively poor sales (which would not bring sufficient revenue for the game). The Lost Vale would have been accessed from the locked double-doors at Bonecrusher's cave on the Plateau (Covenant had found proof of this from Origin's own mouth, but alas, the link no longer works).
This Vale would apparently offer an additional adventure for the Avatar during his stay in Pagan, featuring the other three Zealan gods and a shield with their symbols, broken in two. New foes and friends apparently also show, as well as additional spells.
All we have about the Lost Vale are the screenshots which are concrete proof of what was to come, however a fanfiction was also written, although by a secondary source, to show what might have taken place in the Lost Vale.
See also: A Brief History- Ultima VIII: The Lost Vale (YouTube video) by Gaming with Zack.
Some screenshots were released to show what the Lost Vale would be like. They are available on this site in a gallery with explanations for each picture, as well as at other locations available in a zipped file, including:
Amazing Dragon has written a fanfiction about The Lost Vale. This shows a story after the Avatar left Pagan, starring Devon and the other survivors of Tenebrae. The Lost Vale was originally intended to be an additional adventure for the Avatar to go on, so this fanfiction does not hold true. However, it still makes a good read, and shows Amazing Dragon's interpretation for the Lost Vale screenshots.
Till some time ago, virtually nothing was known about the plot of the Lost Vale, apart from the clues offered by the screenshots.
Now there are two articles providing decent hints to the plot. One is the old advert below, which is available at the following locations:
HIDDEN WORLD UNVEILED IN THE LOST VALE
======================================
So, You thought you'd been everywhere and seen everything while playing
Ultimar VIII: Pagan. This fall you'll be able to explore a land you never
knew existed in Pagan when you play The Lost Vale, the "add-in" game to
the latest adventure in the Ultima series. ORIGIN plans to release The
Lost Vale during the first half of the fall.
In The Lost Vale, you'll discover a forgotten valley created hundreds
of years earlier by the Titans of Earth and Water. The Titans imprisoned
their enemies inside this hidden world, when they commanded the walls of
the valley to rise in the largest tomb ever created. As the Avatar, you'll
realize the secrets of this lost civilization could lead to powerful
alliances in your ongoing struggle against the evil Guardian. You'll
battle new monsters unique to The Lost Vale and you'll search for magic
items and acquire increased stats you can use in the outside world of
Pagan. There's the City of the Ancient Gods, which is suspended in clouds.
There you'll look for advice that could help make you one of the most
formidable beings to ever set foot in Pagan.
The Lost Vale will add several hours of game playing to the world of
Pagan. And since it's an "add-in" disk, you don't have to finish Pagan in
order to explore The Lost Vale. Just install it and begin your journey
inside this game within a game.
Current system requirements for The Lost Vale are:
IBM-PC, 486/33+ or 100% compatible system
6 MB of hard drive space
Core game of Ultima VIII: Pagan installed on hard drive
4 MB RAM
256-color VGA graphics
MS-DOS 5.0 or higher, mouse
MUSIC (optional): Ad Lib, Sound Blaster, General MIDI or
100% compatible sound board
SOUND EFFECTS (optional): Ad Lib, Sound Blaster or 100%
compatible sound board
Expected retail price: $25-$35
The other article is information provided by Sheri Graner Ray, lead designer of The Lost Vale, to PC Games That Weren't. The original article is available at PGCTW's The Lost Vale page, but I am including a copy below just in case something happens to the original.
Written by Sheri Graner Ray for pcGTW, November 2005
The story of Lost Vale was that a group of people had been shut off from the main population of Pagan when the Ancient Gods disappeared. They were isolated for a very long time. However, during this isolation a terrible tragedy involving the deaths of two young boys had befallen them. This tragedy caused a schism in the population with each side blaming the other for the deaths. Neither side had spoken to the other for a decade. It was up to the player to "awaken" the Ancient Gods and heal the schism between the people. To do this, the player had to ascend to the very cloud city where the Ancient Gods were believed to live. There, a terrible surprise was uncovered. The Ancient Gods were not asleep, but actually had been imprisoned. The player had to figure out how to release them. The cloud city appeared abandoned, but was full of traps and tricks and was very dangerous.
As a side note, it was for this add-on disk that the "tiny-tar" spell was developed. This was a spell the player would be able to cast upon him/herself and make themselves shrink. I believe this was developed by John Watson. We got such a kick out of a teeny tiny avatar running around the world that we worked it into the plot line. At one point, to get into the ruined temple, the player had to cast the tiny-tar spell and creep in through a crack in the wall. Great fun!
Many thanks to the anonymous visitor who posted in my forum about the Lost Vale page at PC Games That Weren't.
In November 2009, Sheri Graner Ray continued to provide clues to The Lost Vale by means of two blog posts (thanks Natreg Dragon for pointing them out):
Another interview with Sheri Graner Ray appeared on 3rd March 2013. In this interview, she discussed The Lost Vale and Arthurian Legends. The first page, which is about The Lost Vale, discusses features of the expansion as well as reasons for cancellation.
On 21st March 2014, The Lost Vale plot documents were released at The Ultima Codex.
The latest discovery concerning The Lost Vale appeared on 30th September 2005 when Gromitron posted a topic in my forum claiming that he possessed a one-of-a-kind box of this unreleased expansion. In a later post (6th October 2005), he posted a link to some scans of the box (Wayback Machine). With Gromitron's permission, I am hosting those very same scans here.
Gromitron later auctioned the box and sold it to someone for $1,923. Although there were doubts as to whether the box was authentic, Denis Loubet (who did the box (and other) art for most Ultimas) confirmed its authenticity on the last day of the auction (19th October 2005):
I have researched the cover and tracked down a person who remembers it. It
is authentic, and most likely a cover done by the Origin marketing
department for a never-released addition to Ultima 8.Denis Loubet