Quote Originally Posted by khelvan
Does anyone have any experience creating them? Does the full set of "Interface" files from the Roman culture have to be copied over to the new culture, and then changes made on top of that?

When the changes are made, can they be packed into patch_1.pak, or do they have to be found in a different .pak?

For some reason, our culture-specific GUIs show up when the other .paks are unpacked and deleted, but not when we pack the files into patch_1.pak.
I used both approaches.

The modified files of ui\ROMAN\INTERFACE were packed in patch_1.pak. But it was for the version compatible with RTW 1.2. Now it is more difficult as RTW 1.5 has its own patch_1.pak. I haven't tested if patch_2.pak would work, although it didn't in RTW 1.2.

The barbarian factions had a UI based on the BI interface, and the full set of files in ui\BARBARIAN\INTERFACE was included, even those non-modified files. I didn't try to include only the modified ones.

Sorry if this is not very informative.