The expansion applies not only to the game in general but in subtly different ways to each of the three main areas of the game, namely Hibernia, Albion and Miguard. To be honest, you could as easily be under any one of the three and not really notice much difference. That’s not a criticism as such, as underground is the same pretty much anywhere you go in real life, but a bit more effort on making things noticeably different would have been good.