If Firaxis knew that e.g. Air Superiority was broken then IMHO that is unprofessional of them to release it. This is a “showstopper” bug IMHO because the software is not conforming to specification (i.e. it is not behaving as the game rules suggest).

No, that’s not a show-stopper. Nobody’s going to die from an air-superiority bug in a game, and applying medical-equipment or flight-control standards to a game is a false analogy. We don’t know if fixing the bug might have caused Firaxis to miss a contractual deadline, which would have “stopped the show” in a much more concrete way.

BTW, have you ever seen any software that conformed to the spec in every respect no matter how trivial? I’ve seen a lot of software in my over-a-decade in this industry, and I don’t think I’ve ever seen any that met that unreasonable standard. Half the specs I’ve seen were self-contradictory in some subtle way or other (specs have bugs too), so it wouldn’t even be possible. That’s not a workable definition of “show stopper”; such a definition must necessarily include impact/severity, frequency of occurrence, cost to fix, damage to reputation if not fixed, maybe even professional pride, but it’s never as simple as people here seem to think.