So having at least briefly touched on just about everything that seems vital, I thought I might try firming up some of the material to try and get things to a remotely testable stage instead of just pontificating about it all on the internet.
Unfortunately, I'm now having a big angst over pretty much the entire underlying mechanics of the game. It's sparked specifically by an attempt to flesh out the lineages I discussed previously with some actual rules.
Fundamentally, Attribute-based success and the damage system I have right now do not seem to support the distinctions and characters I want to give the different lineages. They fall into an awkward middle ground: sparse enough that adding in new specific rules seems over-crunchy, but specific enough that there's no obvious leeway for minimalist rules.
The simplest possible example is probably strength. There are several lineages that could reasonably be marked out for their brawn: crocodilians, varanids and heloderms all come to mind. However, in the system I've outlined (which I think has many good points, otherwise I wouldn't have picked it) there is absolutely no provision for variable strength between creatures. There is no Strength or Physical or Body attribute. Damage is intrinsic to weapon types and the Wounding system offers no room for strength variation. The skills are broad enough that adding a modifier to any based on a creature being strong would cause all kinds of logical inconsistencies. Of course, I can add in a trait: the Strong creature gains a +5 bonus whenever being Strong would provide an advantage.
Next, armour. Chelonians are the main point here, but other creatures ought to have natural armour (including some non-reptiles, like armadillos). Okay, we can give them an innate armour value, let's say 8 (tortoiseshell is damn tough, and frankly there aren't a whole lot of other advantages they're going to get). But it's both beardy and illogical to let them wear ordinary body armour on top of that as well, so we need a provision. Okay, armour comes in types. Chelonians count as wearing carapace armour at all times, which will in itself prevent that. What about less-armour critters like crocodilians? Well, we could give them armour 2 or 4, but that's hardly ever going to be useful, to be honest. Or we could let it stack with the armour they're wearing? Now we have two different rules for how armour can work, making things complicated and inconsistent. Maybe we should scrap that one.
Chameleons, of course, have good vision because of the separate eye movement. Frogs are really good at spotting movement, but otherwise not so hot. Neither one is really covered by Perception, so we'd ideally want a separate rule for that if we want it to feel specific rather than just like a generic bonus.
More interestingly, chameleons are of course chameleonic. That really wants to be in here. Although it should only apply when they have a reasonable amount of skin on display if we're aiming for any realism at all. And it's technically mostly associated with emotion, you could do interesting things with that if you want to spend a couple of pages writing rules for it.
Geckos and basilisks are fast. There's really no rule for speed in here, except a vague movement speed one. Again, I could add a vague "whenever applicable bonus", but it feels unsatisfying. Their climbing would need another one, because climbing is part of... Agility, I think?
...and so on and so forth. Venomous skin here, jumping there, regeneration yonder. And this is without getting into the weirdness of other genera.
It feels like things are pulling in different directions here. Some are crying out for detailed, crunchy rules; others seem to really favour a very loose ruling-based system. Strength, speed and endurance come up regularly as lineage traits but can only really be represented by either detailed and specific rules, or by a vague handwavy rule. Other interesting and characterful traits, like skin-breathing and tail-shedding and ultraviolet vision, need some kind of specification to make them at all usable. I don't want to turn all of this into bland "+4 to X" rules à la recent editions of D&D, because then you lose the whole thing about actually feeling like reptiles. On the other hand, grafting on highly specific rules to a fairly skeletal core mechanic seems problematic.
I also can't help feeling that this is just one instance that I've noticed. There were rumbles of disquiet earlier when I was thinking about magic, and realised the system as it stands doesn't especially allow for resisting spells or even having variable effects. Similarly, once we get to detailing tech, I suspect I'll find that it's difficult to characterise things like bionics with no physical stats to modify. In some ways, the system I've got would actually be far better for a game where you're all playing very similar characters and don't have to worry about statistically-significant variations in anatomy.
So I'm pretty stalled on what to do here; reluctant to tear the guts out of the whole thing and start again, but not really sure how to proceed with what I've got either. And I've got a rotten cold right now that isn't helping at all.
More to follow, undoubtedly.