Size is a very important aspect of species in my setting. So I wanted to run these Silhouette-based special abilities by people for their opinions on cost and concept.

SMALL (-5 XP)

Your species is smaller than average and counts as Silhouette 0. You multiply the Brawn derived statistics for Damage, Encumbrance Threshold and Wound Threshold by your Silhouette. This means that small species do not deal any additional Brawn damage to attacks, their Encumbrance Threshold is 5, and their Wound Threshold is not improved by their Brawn. However, your size makes maneuvering in small spaces much easier than for larger creatures and easier to sneak around. You gain 3 on all Stealth checks made in areas built for Silhouette 1 or larger creatures. Also, appropriately sized weapons, armor, and gear is more expensive, increase their cost by 50%.

LARGE (-10 XP)

Your species is larger than many and counts as silhouette 2. You multiply the Brawn derived statistics for Damage, Encumbrance Threshold and Wound Threshold by your Silhouette. However, you can barely fit into most human-sized places. When maneuvering and acting within spaces not designed for Silhouette 2 or greater creatures, you suffer 3 on all Brawn- and Agility-based skill checks per Silhouette difference. Additionally, appropriately sized weapons, armor, and other equipment is more costly, increasing their cost by 50%.

Example: A Silhouette 2 species trying to perform a Brawl check in a human tavern (silhouette 1) would suffer 3 to the check.

HUGE (-15 XP)

Your species is larger than average and counts as silhouette 3. You multiply the Brawn derived statistics for Damage, Encumbrance Threshold and Wound Threshold by your Silhouette. However, you can barely fit into most human-sized places. When maneuvering and acting within spaces not designed for Silhouette 3 or greater creatures, you suffer 3 on all Brawn- and Agility-based skill checks per Silhouette difference. Additionally, appropriately sized weapons, armor, and other equipment is more costly, increasing their cost by 100%.

Not sure I agree you should be multiplying damage by silhouette. And gimping wound threshold for small? ?

An adult chimp is about 1 meter tall which is silhouette 0. They are still stronger than the average adult and no less tough. If you want the race to be typically weaker start the race’s strength at 1. You can lower the races starting wounds to reflect fragility. The reverse applies for larger.

I agree silhouette should effect encumbrance as that represents bulk as well as weight.

Increasing equipment costs should only apply when they are in communities outside their own. But even then I cite when the Hobbits visited Bree. The Prancing Pony Inn had Hobbit sized beds to cater to the small travellers even though it was a Human settlement. It should be situational.

Interesting, adding an additional 8 (probably) Damage to Brawl checks for huge characters is a lot. If Combat is a smaller part of your regular groups sessions then this should work. If Combat is more common than other encounters then this all needs rethinking.

In Star Wars smaller species tend to have start with a Brawn of 1 while larger species often start with a Brawn of 3. For my table that is a nice and simple way of reflecting inherit advantage physical prowess to a larger build.

I agree with others here. Silhouette 0 shouldn't really cost anything XP-wise. If the species/race is weak, just drop their starting Brawn to 1 and their Wounds a bit. You'd be within your rights to grant them a boost die to checks to hide, or a setback to checks to use human-sized equipment, but these sorts of situational benefits and drawbacks will likely balance out. That seems to be the FFG philosophy in Star Wars, anyway.

If you want to include really tiny races (like brownies or fairies or something), I think it's probably worth giving them bigger game drawbacks and granting extra XP for it. I'd check FFG's Star Wars books for how they treat tiny creatures and borrow some ideas from that.

Being Silhouette 2 might be worth some bonus XP. I imagine it'd be tougher to sleep a centaur at a Holiday Inn than it would to sleep a halfling. I wouldn't mess with their derived attributes that much, though; just pump up Brawn and Wounds. If the species is horizontal, like an intelligent horse or a centaur, you might grant them some extra Encumbrance (see the riding beasts in Star Wars for ideas on how to do this), and charge them for that aspect of it.

Being Silhouette 3 is probably even harder. Again, look at statted-out creatures of that silhouette for some ideas on what Wounds and Brawn should be. Then maybe grant some bonus XP for the inconvenience of being the size of an 18-wheeler in a human-oriented world.