So, I wanna talk a bit about one of the odder things I'm doing with Esoteric Enterprises, which is the Spook class. Basically, the idea is that the Spook class covers all the different non-human PC types. So vampires, ghosts, fairies, werewolves and all sorts of other weirdness are possible as player characters.
The class is a toolbox, so you can emulate different monster archetypes. In this, I've taken a lot of inspiration from the old World of Darkness games and the wide variety of monsters there. The big difference is that WoD is prescriptive with it's setting. It says that vampires work like this and there's an underlying structure to them. I want EE to pull away from that prescriptiveness. Vampires (for example) aren't a coherant species found all over the place. Instead, each vampire or brood of vampires is unique and independent, with its own quirks and abilities and folklore. There are bloodthirsty and canibalistic undead creatures all over the world, sure, but the similarities between a ghul and a wendigo are mostly coincidental.
How this works in practice is like this: you pick the 'type' of Spook you want to be. This basically just covers what the spook is made of and what their biology is like; undead, made of stone, human, intangible etc etc. These have some mechanical impact; an undead spook, for example, doesn't need to worry about diseases, but can't be given HP back with medicine. There are a few different types available, covering broad categories like fae and ghosts and so on.
Each level, the Spook picks up a 'power'. These occupy a similar space to spells for a spellcasting character. However, powers are fairly low in power level, and always-on. They're things like 'you can see in the dark' or 'you can heal by drinking blood'. Since the spook gets one every level, most are pretty simple.
At first level, the power you get is randomised (same as the spells a magic-user gets), from a short list based on your type. So, like, a fairy is picking from a list of nature and trickery related powers, while the undead's powers are all either brutal, spooky or gory. After that, powers are grouped by themes, and you're limited to taking powers with a theme in common with powers they already have. Basically, this means that if you get a sneaky-stealthy ability to start with, your next abilities will mostly also be sneaky-stealthy until you start branching out.
Pretty much, the class is based off LotFP's elf. Saves, XP totals, all of that are as the elf. Instead of spells, you get powers.
In theory, what this means is that spooks can be lumped into rough groups, with low-level members of those groups all being roughly similar. But the more powerful members will diverge more and more to become increasingly weird and unique. Like, a first-level spook that's modelling a vampire is probably undead (so vulnerable to turning and holy water, but basically safe against poison), and heals by drinking blood. And the next few levels, they're gonna pick up stuff like a bite attack, or being bolstered by darkness and weakened by light, or super-strength. Typical vampire stuff. But higher level vampires will have branched out into other themes of power and have their own weird stuff they do. So, one vampire has addictive blood and lots of social manipulation, while another experiments with reanimating dead flesh, and another is a pure combat monster with claws and fangs.
This applies to spooks that aren't vampires, too! The higher level the spook is, the more weird and divergent the powers it's picked up are. All low-level ghostly PCs are gonna be pretty similar, but high-level ghosts will have all sorts of mad shit they can do.
This creates a wide variety of different weird monsters, and a distinct play style for monsters overall. Where a spellcaster has a limited number of chances to totally negate an encounter (spells like sleep or hold portal or whatever), a monster instead has a small, but slowly growing, list of problems that are just easier for them to solve, statically. Plus, by pushing all the weirdo PCs into one 'build your own monster' class, you get both a wide variety of inhuman PC archetypes, and a game where 5-out-of-6 classes are human, and so probably a human-focussed campaign.