In my original version of UW1, the game was much brighter than it is in the GOG version. Even with a light source, in the GOG version, I can't see across a moderately large room. Is there some way to adjust brightness to make it a little easier to see what I'm doing??

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Later note:
Okay, I see what's going on now. In the original game, you could delete data/shades.dat to remove all the shadows. I had done that with my original copy, long ago, and had forgotten it.

However, in the GOG version, this file does not exist at all, so I can't remove it.

So, is there any other way to adjust brightness in the GOG version of the game?

Hmm, you can open the game.gog file with Izarc or any other archive extractor utility which can open ISO images. That file is actually cdrom image.

Inside of that image, there is directory UW (and UW2). You can copy those to your hard disk. inside of the directory is full installation of the game, and there (in data folder) you can see shades.dat file (which you can removed).

After removal, modify dosbox conf file for Ultima Underworld to mount the directory from hard disk where you extracted your game, and run the game from there.

Oh!! Okay, so *that* is what game.gog is... I'd seen references to it elsewhere, but didn't know what it actually was. Thanks!!

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Later: yep, I copied it to game.iso, and Gizmo Manager can mount and read it just fine! Of course, the image is read-only so I can't delete that file, but it proves your proposal.
Thank you again, GoingDown !!

You can extract the files and build a new ISO from them (renaming back to game.gog afterwards, of course) or adjust the conf file to run the files directly rather than from within the image.