Don't give up on me, Stuart!
Okay, we've got a couple of misunderstandings here, most likely due to my lack of knowledge. I want you to know that I really - and I mean really - appreciate the help you're giving me. And also that I do not consult you, unless I've tried (and tried, and tried, for hours or days) and cannot solve something. I am not lazy. At all. Ask my wife.

Back to the topic: what I seem to need - the bare minimum - to get the main part of my mod working (as in: real-life practical experience, in other words: what the game/mod does om my computer), as I said several times before, is the default_ini.lua, the loading.lua and the startscript.lua. If one of them isn't there, the mod doesn't launch or doesn't launch correctly.
I've re-read the entire thread, but can't find any (new or overseen) answers...

You are correct: I'm trying to get the game to not load the root menu and the logos and the cutscenes. I achieved that in Dark Horizon, but for some reason I cannot in Tarr chronicles. Hence the question as to you knowing about any other files (apart from the three former mentioned files) that in TC define what happens in the game. A valid question, I believe.
You mention in your last post that I should look in the "system folders" (plural) for the startup stuff. But I only see one system folder (under interface), and there's nothing related there. If you mean the folders from the different systems, they only contain the startscript.lua as relevant files, and I already am working with that file, as you know. So again, I arrive at the same point: since in my startscript.lua afaik no cutscenes or replics are called, how come they appear? So, in spite of your answer, I'm left with the same, unanswered question: Are there - apart from the startscript - other files in TC (that are not there in DH) that can call cutscenes and replics into the game?
In your post from Sun Jun 14, 2015 11:51 pm you said that I didn't need to load anything, which I understood as: I don't need the loading.lua. But that wasn't so: my mod won't run without the loading.lua. Not even with the bare-bones version of the mod (the famous three files instead of all the 220 modified luas).

In your post from Fri Jun 19, 2015 12:38 am you said that I didn't need the "toGame" function in the loading.lua, because it already is in the default_ini.lua. But on my computer the bare-bones mod won't run without the "toGame" function also in the loading.lua file.

FYI: I'm not yet at the "ripping-everything-I-don't-need-out" level. First I want to get the bare-bones mod running. Then the complete mod. Once I'm there, I'll try to clean up the game, by throwing everything out the mod doesn't need. Why waste disk space, right? But that's something for the future.
"Please bare with me a bit longer, my master", said the humble and unworthy pupil, "and forgive me for my ignorance..."
