|Art by Luigi Castellani, from Silent Legions.|
Place. I'm sure there are one or two examples, but I can't think of a Lovecraft story off the top of my head in which people are just minding their own business and a monster comes along and goes at them. In almost any case, the monster is tied to a place; that doesn't necessarily mean a habitat, but it's definitely a trend. Sometimes it's shocking because the monster doesn't belong, but a lot of the time the monster does belong -- and it's you who doesn't belong -- or the monster takes a place and begins warping it so that it belongs, like Joseph Curwen or the Deep Ones.
Revelation. A big briefing in the setting that says "yes, these are bad things from outside space and time and they threaten reality and blah blah blah" is not a good way to be introduced to a Lovecraftian horror. This actually works differently from a lot of monsters, where you want there to be some buildup. "Going to the woods? Watch out for the owlbear!" works, but I'm not convinced it works for something where the knowledge of it is supposed to be threatening. I'm looking at you here, Mage.
I guess what I'm saying is that a genuinely Lovecraftian creature is less about the beast's characteristics than about its context. The monster has a place and a history, which basically means that it has a setting and a story.
Which may explain why Lovecraftian critters shorn of their context -- like in the CoC monster books, to be perfectly frank -- don't really mean much. And it does remind us that, as I mentioned in But with all the Pokemon-collecting, it can be easy to lose sight of that.
(Once again, I come back to how good the GM advice in the Call of Cthulhu d20 rules is.)
|Pointlessness of actual game: 100%.|
Norms. One good idea is to have the monster violate some kind of rule or norm -- like a physical law, perhaps as addressed by the rules. This could be as simple as having them violate the law of gravity by floating, or it could be something weird like violating causality or experiencing time in reverse. It doesn't have to be big, but it needs to be something that indicates that this is not just a piece of hostile wildlife like an owlbear or a human stand-in like an orc or a supervillain like a lich. Obviously this is easiest in a realistic setting, because just doing monstery stuff is a violation, but whatever the rules of your setting are, bend them.
Language. If you're going to have an indescribable monster, a primarily verbal medium like an RPG seems like an ideal place to have that. Could you run a scene with a creature you literally can't describe? I kind of want to try it now. But I do think that, nine times out of ten, a very detailed, Barlowe-y approach to a monster is not gonna get you anywhere in a tabletop game; things have to be described in a shorthand kind of way -- and sketchy description that focuses more on verbs is actually going to be well-suited to that. I'm not going to pause to describe the creature any more than I would with a gnoll or a bugbear, but I was always going to use words to describe its actions, so it costs me nothing to say that it "lurches" or "shambles" or "suddenly appears" rather than that it "moves."
I guess part of what I mean about laws and language is that you have to consider whatever your setting establishes as a norm and then mess with it. If your setting already has Ilithids and aboleths and gricks and giant squids, then you're not going to be able to just throw down some tentacles and call it a day. (Well, I might do this, but then the mythos-y elements in my D&D setting are more pulp adventure than horror; I'm trading on the known tropes rather than trying to create actual Lovecraftian dread.) (You could have just said "like in Hellboy, right," James.)
Actually, maybe all I mean is go look at Hellboy for a setting that has cyborg apes and ghosts and werewolves and vampires and still manages to make its cosmic horror monsters qualitatively different.
And of course, that's leaving out the old Kirby-anecdote approach (you know, the one where Kirby goes to the comic company and some youngster says he's going to do things "the Kirby way" and Kirby says "doesn't that guy realise the Kirby way is doing it your own way?" Words to that effect, anyway). After all, the whole point of Lovecraft's "anti-mythology" was to escape boring old ghosts and goblins. If Cthulhu is too tamed, skip it and do something else.
So anyway, that's just me thinking about the topic late at night by myself. I will now take a moment for obligatory plug time!
Speaking of Lovecraft and monsters, I wrote a thing -- a little ebook that is a Lovecraftian (I hope) horror story set in the Viking age. It's called The Barest Branch, and you can buy it on US Amazon, buy it on UK Amazon or pick it up in both Kindle format and .pdf on DriveThru. You might like it, and it's not very expensive.