Up to what point is Rule 3 enforced? Is it just LUA mods or texture+sound mods as well? I ask because some runs I've noticed UI skins and weapon skins. (Not trying to call people out or anything, would just like to know for my runs)

ima guess lua mods, since skin mods (mod_overrides) really doesnt affect gameplay that much while lua mods tell you extra information.

Well, for me "no mods" means "no mods whatsoever" - nothing that comes from outside the game itself. I haven't seen all of the runs so am not aware what exactly you're referring to, but am of the opinion that if you see something you call it out. I would even suggest it be required to show after the run that you have no mods in your Options --> Mods/LUA Mods.

When we said No Mods, yeah that's no mod at all. We prefer to have vanilla runs to be sure of the authenticity of the run. Some Mods can give you extra informations like the number of pagers, it's part of the game to remember how much you used. That's for the extra informations mods. For skins it's more difficult to say what we should tolerate or not. But an ex-mod with me said me that some skins of the HUD, can help to not hide some part of the screens, change some informations of the game in a minor impact, but change. So, to be sure and not loose hours to decide if it's legit to use that mod or not, we prefer to say "no mods at all".

I know it's part of your personnality sometimes to customise your game for identify you, I understand. But it's more easy to us to verify like this.

How come this run has been validated when there are clearly mods being used (buy all assets and information about drill)?

Oh damn that was a tricky one. I did not notice the buy all assets and been fooled by the language. Did not notice that was for signal drills jammed. Thanks for the report. ;)