Is there a way to force the game to start in windowed mode, either from the command-line or by setting options in a config file? I can't change it from the in-game settings, because I can't access them, because the game is confused by my admittedly-weird monitor setup and I can't see the settings. Think I could sort it all out if I could just force it into windows mode at startup.

Huh. Thanks for the info; I'd found that file, but mine was blank, so I didn't know what options to set. I've tried using your options, yours but setting r_fullscreen = 0, just r_fullscreen = 0, and just r_fullscreen = 1 - they all seem to start it in fullscreen mode regardless. I also noticed that in addition to userdata/settings.ini, there is a userdata/Abbeycore/userdata/settings.ini, so I tried all of the above in that location too. No dice.

Oh for goodness sake. A bit more poking around found me additional copies of settings.ini in:

./settings.ini
./userdata/settings.ini
./userdata/AbbeyCore/userdata/settings.ini
./game/settings.ini
./game/x86_64/settings.ini
./game/x86_64/userdata/AbbeyCore/userdata/settings.ini
./game/userdata/Renowned Explorers International Society/userdata/settings.ini

Looks like setting r_fullscreen=0 in this one:

./game/settings.ini

actually does something, while all of the others are ignored.

OK, sorry. I didn't actually test this; I only reported the file that gets modified by the game itself. I install all my games as root, and have to jump through extra hoops to even allow games to write to the game dir (which they shouldn't be doing in the first place). Thus I have a complete list of files modified by the game (abbeycore.txt and files under userdata/Renowned.../ for this game). I don't know where all those copies of settings.ini are coming from for you, either, since my game only has one copy (game/settings.ini) other than the one I reported, which I just assumed to be the defaults. Weird.

The "For goodness sakes" wasn't aimed at you mate; it was aimed at the fact that I apparently have 7 settings files, only one of which actually does anything. Thanks again for the options names, without which I never would have worked this out.

I have changed the way I do things. I used to log every written file (either by making the dir temporarily writable or using strace) and change permissions or make soft links. Now I just added a "-w" option to my game launcher script, which then uses unionfs to make it writable. I do something similar now on all my windows and dosbox games to keep the installation "pure", which doesn't always work well e.g. if a game opens every single file in write mode, causing my shadow copy to be a duplicate of the game. Currently I use that option on 15 "pure native" games, although some of that may be excessive.

Balrum - convig.xml, debug.txt, files/cache, files/saves

The Bard's Tale - I think it just tests for writability somewhere; it doesn't leave anything behind.

Bionic Dues - RuntimeData/

Call To Power 2 - ctp2_program/ctp/... actually, this isn't a GOG game, but the open source port of ctp2, which has numerous issues.

Eador Genesis - Eador.cfg, gamelog.txt, save/ (another non-GOG Linux binary)

Edna & Harvey The Breakout - actually, never mind on this - GOG has updated their version and I haven't retested.

Battlevoid Harbinger - in Linux64/harbinger_linux/ - save settings.xml user

Kerbal Space Program - a horrible mess.

Renowned Explorers - well, I already reported what I knew there. It obviously depends on what you do, and in what order, so some of my other reports here may be inaccurate, as well.

Rezrog - I think it just tests for writability somewhere; it doesn't leave anything behind.

Ronin - preferences.ini save.ini

All 3 of the Shadowrun series - DumpBox/ (this one always aggravated me the most, because I would forget to fix it and it wouldn't hang until any time a chapter ended).

StarBound - storage/*

Thanks!

I like the idea of using unionfs or any such system, but I don’t want to add too much dependencies to games installed with ./play.it

The solution I’ve been using for a couple years with success is a "farm" of symbolic links, pointing either to read-only system-wide files or writable user-specific files. The drawback being of course that I need to know the list of files the game needs to write into.