Thanks a lot, that's very profound! You've totally got the point about how player's mood influences the game tone. Yes, people are kinda not supposed to play during their breaks. If you do something you enjoy (like play a game) instead of chatting about "Patrick's new car" (fictional situation) you may be seen as rude. I never understood that. This game is a way to still enjoy breaks in the way I want.
While Intruder aims big offices for the spy/hacker theme reason, the same tone influence actually works pretty fine elsewhere: at school, in public library, retail job, etc. Whenever you play in a situation where you prefer to do some sneaky dice rolls (because you do not want to talk about your hobby with strangers, because you're not in gaming-friendly space, etc) it will eventually take part in the "sneaky as a spy" mood.
Thanks again for your input and hope you had fun reading it!