While the roots of this exist in 1E, I’m sure that this concept really dates from some later edition. This is one of those really interesting rules that I like for all sorts of reasons, and then hate because I can’t decide if it is a typology or taxonomy (and, in fact, it’s a bit of both) – the minute you start kitbashing your own monsters and have a significantly different cosmology from the implied setting (no matter how much you are applying your own rules of Gygaxian Naturalism) is the minute that the given Types have a tendency to fall apart. That said, the whole Tag system may also give some help in that.
So, “old rules” I had the Dearth – which wasn’t quite Undead, wasn’t quite a Fiend, wasn’t even automatically an Abberation – almost more of a Monstrosity according to the descriptions. Except of course that it “feels” more like a Fiend or an Undead. But, now I could simply say it is any of those types (as fits best) with a Dearth tag.
That example is pretty easy. The one that gets a bit more dicey for me is Trolls – in my head, Trolls, Giants, Ogres, and Goblins are four categorically different things. In the new version however, Trolls, Giants, and Ogres are “the same thing” while Goblins are Humanoids. Now, in some ways this is not such a bit deal – except when we get to Rangers and they get to choose Enemies that they get bonuses against. I suppose that the best answer is to simply say that they roll with it – but then I’d have to figure out what counts as a Humanoid given that my list of humanoid races is way, way shorter in some ways.
I do really like the idea of unaligned creatures – that is much more elegant than the old neutral catch-all. Similarly, I like the appendix in the back for “normal creatures” (even though it includes wargs and winter wolves and a handful of other things that seem to be anything but normal) but I still hate the whole NPC’s as a stat block as opposed to being a character class. Yes, I’m sure that this will save all sorts of people all sorts of time – but I really don’t think it takes that much time to write up (or end up having memorized) an NPC either as a “0-level” or as a leveled character class.
I’m hoping that the DMG actually clears this up – the relationship between the “average man around town” and a PC. In 1E it was clear that the PC was an exceptional, heroic type – but that isn’t quite so clear in this set of rules. There is a hint or two of it, but it is unclear what makes a Noble get two Hit Dice and a Parry and Cultists also get two Hit Dice and Dark Devotion or a Scout gets three Hit Dice plus Keen Hearing and Sight. It all just seems to be a poorly thought out way to make different professions different without giving them a character class. Or something.