No Not Skill Synergy Burn, Skill Synergy, Burn!
It seems to me to be the logic underlying TPs, along with context. I like the idea more in practice than in principle.
Damnit, I meant to say "in principle more than in practice".
I've given some thought to "skill synergy" and "supplementary skills" in the past, and decided to let the logic piranha at the results.
The way I see it, the real priorities are:
1. Any synergy mechanic must give the player a reason to
want to have the supplementary skills, in other words there has to be an advantage that justifies spending the DPs (or whatever he uses to express his development choices in the context of the character sheet, depending on the game system.)
2. No amount of ranks in any number of supplementary skills should give you
so much of an advantage as to really change the power balance of the game. Always
useful, but never so useful that lack of them becomes effectively "suicide by dumb player choices".
3. Whatever mechanic is used to simulate this can't be "too fiddly", if it noticeably slows the game or causes a paperwork/info tracking hassle, it's not worth it.
Personally I've played ICE games almost exclusively since the early 80s, so I tend to think in terms of the 5/2/1 diminishing return for skills. I long ago accepted the rationale that the first 10 ranks are "the fundamentals", the next 10 are "mastering the skill" and everything beyond that is "finishing touches".
With that in mind, what I've come up with as a tentative solution for the issue of supplementary skills is this:
Supplementary skills can add to the bonus of the primary skill in specific situations, for example Tracking skill can add to Foraging & Survival if you are foraging for something
that leaves tracks. Such skills modify the primary skill by +1 per skill rank, with no accounting for stat bonuses or any other considerations. Only the fundamentals of the supplementary skill apply to the primary skill, so the +1/rank bonus maxes out at +10 for any given supplementary skill. More than one supplementary skill can be applied to a primary skill, to a maximum of 3.
So... you can modify skill rolls using related skills, but only up to +30, and in order to get that +30 you have to have at least 10 ranks in 3 other skills that all apply to your current situation.
Thoughts?