If you read the anecdotes and the counter-examples in this thread, it seems to matter. The idea seems to be that a game is not dead for as long as someone is playing it. Many criteria in the OP revolve around the personal experience which may, as we all know, vary a lot. My point was: those are...
So, how do you know a game is dead? You have no way of knowing that there are no solo gamers or isolated groups somewhere playing the game. You might have problems finding players for a particular game, but somewhere on a Pacific island or in Western Elbonia there might be a vibrant community...
Things you could (but you don't have to) use languages and/or dialects for in a RPG:
Provide characters with a spoken identity. People can spot a dialect pretty quickly and in many cases determine where the speaker is from (or at least where they are not from).
To pass as a local/native...