Attribute Substitution and Defaults
 

Curious if this is right, or too over the top.

Say I have a DX 10, PER 15 PC. I buy the Attribute Substitution perk "Guns/Pistol Based on PER" and drop [1] point in it. Okay, I have a Guns/Pistol skill at 15.

Now say I pick up a rifle. Guns/Rifle is a DX-based skill, but also says it defaults to Guns/Pistol-2.

So, am I shooting my new rifle at skill 13?

Re: Attribute Substitution and Defaults
 

Possibly. Its up to the GM. Attribute Substitution is optional and when allowed the instance for what it is bought for should make sense in the setting.
What justifies that Guns/Pistol as a Per based skill? Is it intrinsic to pistols in the setting? Maybe some weird targeting mechanism where all you have to do is spot the target and point it in the general direction and some computer does the rest?
The justification may be situational (like a floating attribute) or work all the time. Even then it may not cascade to defaults, though it probably does.

Re: Attribute Substitution and Defaults
 

Guns was just an example.

It seems like it could get abusive if you use it to leverage some skill that a lot of things default off of. Say, Animal Handling.

Now I have Animal Handling (Equines)-15 (spent 2 pts).

Do I get to default Packing-10, Riding (Equines)-12, Teamster-11, and Vet-9?

Re: Attribute Substitution and Defaults
 

Yes, Attribute Substitution has considerable potential for abuse. That's why the GM needs to approve it, and the changes are required to "make sense" which implies the GM should be sceptical. There's also a limit on many Attribute Substitution perks you can have.

Defaulting off an AS'ed skill requires GM judgement, but it should be biased towards "No."

Re: Attribute Substitution and Defaults
 

I've tried to build characters based on the abuse, trying to anticipate what players might do. The 5-perk limit seems to do a good job controlling this, especially since there are so many desireable perks. I see this as working when you need to be good at one thing that's outside your best attribute, but if you want several, the better bet is Talent, 20 points for +4 to the half-dozen skills most central to your concept and a reaction bonus from people who would respect that. The GM not only has to agree that the Attribute Substitution makes sense in general, he's free to stipulate the attribute used for any particular skill check, whereas Talent applies regardless of attribute, so on balance, I haven't found Attribute Substitution abusive.

To your main point: I'd allow the guns default (different specialty of same skill). I wouldn't allow a HT-based Musical Instrument skill (analogous to Singing) to give HT-based Group Performance or Musical Composition, though.

Re: Attribute Substitution and Defaults
 

I might rule differently in those two cases, and indeed for particular applications of the two cases, because of the way I feel about skill to skill defaults. Those are the flaw here, not the Attribute Substitution. If you do not allow skill to skill defaults at all, the "abuse" issues go away.

The existing method treats "some stuff can be done with more than one skill" as "all stuff can be done with either skill, no not in reality, but we'll kind of guess how much overlap there is and assign a penalty based on how small a fraction that is and call that good enough" which is frankly a terrible model all around.

Re: Attribute Substitution and Defaults
 

This comes up in DF particularly with Lockpicking -> Traps. Lockpicking is IQ but (in DF) normally subbed to DX and raised by High Manual Dexterity. Traps is also IQ but most often subbed to Per or DX.

My ruling is that the attribute used is always what is appropriate. So Lockpicking [12] IQ+3 creates defaults of Lockpicking DX+3+HMD, Traps IQ+0, Traps Per+0, and Traps DX+0 (+HMD to offset penalties for fine work). Put the most typical on the character sheet but use the appropriate one.

Re: Attribute Substitution and Defaults
 

in the example of pistos and rifle default, if I allowed a PER based Guns(Pistol) at all, the rifle default to pistol-2 would return the attribute to DX base.

So: Pistol (1) PER+0 15; Rifle (Default of other Guns-2) DX-2 8.

Because the Pistol skill have the AS not the rifle skill.

But in general terms I wouldn't allow such a slippery slope of a perk.