Rather than having multiple installs from GOG, I like doing an install then copying the game folder to a single DOSBox installation I have (using the D-Fend Reloaded front end) which I keep in Dropbox so I can access it from any PC.

This is normally easy. However, with Ultima Underworld 1, when I check the installation folder, I find a folder UNDEROM1 but this doesn't contain any EXE file to run.

I checked the runnable shortcut:

"C:\GOG Games\Ultima Underworld 1 and 2\DOSBOX\DOSBox.exe" -conf "..\Ultima Underworld 1\dosboxULTIMA1.conf" -conf "..\Ultima Underworld 1\dosboxULTIMA1_single.conf" -noconsole -c exit

Which refers to this config:

[autoexec]
# Lines in this section will be run at startup.
cls
mount C "..\Ultima Underworld 1"
imgmount d "..\game.gog" -t iso -fs iso
d:
cls
uw.bat
exit

Which suggests that the executable files are on a CD mounted as game.gog. Is it possible to extract these files?

P.

The executable and other game files are the game.gog file. A .gog file is an archive file that can be opened with programs like 7zip.

If you look in the autoexec, you'll see the imgmount command that GOG is using to mount the ultima underworld folder.

imgmount d "..\game.gog" -t iso -fs iso

Also note it's directly specifying the 'iso' image type.

I bet if you copy 'game.gog' as 'game.iso' you'll be able to open it in winrar, 7zip or anything capable of extracting iso files. (Can Windows do this on its own with its built-in zip functions? i can't remember. Worth a try though.)

You can open the .gog file directly with 7z.

Too bad you can't do anything and re-7zip it... Was going to do the old trick in Ultima Underworld 2 that make the whole game lit up like daytime by renaming a file.

But once you make a modification and 7zip it again (even to rename a single file) it's unusable by the GoG setup.

7-Zip won't work but the following will:
1. Extract the CD's contents into a new folder and make changes as needed.
2. Open ImgBurn (or similar) and choose to make a new CD image.
3. Add the files and folders from the extracted CD folder into the list.
4. Set the File System to ISO9660.
5. Save the image, then rename to game.gog, etc.

I'm not familiar with the light trick but I've tested these steps and the game successfully starts from the changed image afterwards so I'm guessing the absent file will take effect as expected.

These same steps should work with other GOG games using CD images although this is the first I've tried. Some games check that the CD label is correct as part of copy protection, so if the original image has one you'd want to use exactly the same label on the new image, but this game doesn't have a labelled image so probably doesn't check that.

EDIT: there's also Lights Patch by Gigaquad, which apparently brightens the lighting data rather than breaking it altogether, but I haven't tested this either. :)

Oh thank the Gods I can SEE. Thanks! Worked perfectly. Now I won't get migraines while playing. :p