My technical specialities are zoology & taphonomy & documentary television, with a bit of geology, oceanography and archaeology. I know bugger all about electrical engineering or the chemistry of explosives or quantum mechanics or whatever hard science rabbit-hole the player wants to go down. So I can improvise “There is a CCTV system” but not “and this is what the wiring diagram for it looks like”.
I have 2 people I play with fairly regularly who WILL NOT STOP at one question. If you improvise a Star Wars style land speeder, they want to know its top speed, 0 to 60 in how many seconds, what braking efficiency, main power source, miles per gallon, what capacity is the boot, does it have AI assisted parking, who drove it in Top Gear’s ‘Star In A Reasonably Priced Car’ feature, etc, etc.
I have upon occasion started a one-off game by warning these players: Do NOT ask technical questions about magic, supernatural shit and wibbly-wobbly timey-wimey stuff. There are NO technical answers about these.
I trust that if you play in my adventure Truant Inkwell you will take “a zone of sea-level-pressure water 6,000 metres down” as a great big hint that Here Be Things Wot Don’t Make Sense.
My answer to part two is often “tell me what you want to do.” I decide how hard I want that to be, make a skill roll. Based on the margin of success, and how hard I want it to be, I tell them something like “if you go out to the wire closet on level 4, you can splice into it there.” And then someone has to go do it, which maybe hard, or just a “okay, that will take 12 minutes”. Crit fail gets a plan that won’t work, failure is “you can’t figure out how to do it “.
That’s if I want the idea to be possible. If I don’t, I roll and tell them they can’t figure it out, or tell them a way that would take time or be dangerous or expensive (and which won’t work), depending on the roll, or my feeling about the idea.
We weren’t sure we believed the instruments. A way to convince future players: the pressure hull starts making the going-up kind of creaking noises as you descend.