It's not a
mechanic, but here's a thing that strikes me as
modern when it is found in a RPG: a clear statement of GMing principles.
A related thing, which also generally strikes me as modern, is a clear statement of how actions should be resolved, which makes reference to principles as part of the process.
Even very early RPGs have had reasonably clear statements of action resolution procedures: see eg Classic Traveller (1977), which says (Book 1, pp 2-3, 20), that
Routinely in the course of Traveller, dice must be thrown to determine an effectively random or unpredictable course of action. These dice throws may be made by players for their characters, or by the referee for the effects of nature, non-players, or unseen forces. Rolls by the referee may be kept secret or partially concealed depending on their effects. In situations where the players would not actually know the results of the roll, or would not know the exact roll made, the referee would make the roll in secret. . . .
Saving Throw (also called throw): That dice roll required to achieve a stated effect. . . .
The above listing of skills and game effects must necessarily be taken as a guide, and followed, altered, or ignored as the actual situation dictates.
In some game situations, actual die roll results must be concealed from the players, at times allowing them to misconstrue the reasons for their success or failure. In other situations, the referee may feel it necessary to create his own throws and DMs to govern action, and may or may not make such information generally available to the players.
In order to be consistent (and a consistent universe makes the game both fun and interesting), the referee has a responsibility to record the throws and DMs he creates, and to note (perhaps by penciling in) any throws he alters from those given in these books.
But this is very vague about
when and
why the referee should call for a throw, or make a throw of their own - for instance, is the GM bound to make the throws that players must make for space travel before framing a scene involving a NPC's starship? After all, the success of a jump is just as unpredictable for NPCs as for PCs.
And the text says nothing at all about what the scope of throws ought to be, and how failures ought to be narrated. At best, the referee can draw inferences from examples provided in the rules, although these are not all consistent in their methodology.
A
modern game will - in my view, at least - be much more systematic in how it direct the game participants to use the dice:
when,
why, with
what sorts of outcomes in mind, etc. That's not to say that all games are perfect in this regard - I've posted some complaints recently about Mythic Bastionland in this respect recently, even though overall I like the game and am looking forward to GMing more of it.
For me, the gold standard in the statement of principles for GMing is provided by Burning Wheel and Apocalypse World. A close runner up is Agon 2e. But there are plenty of RPGs that I don't know that might be as good as (or even better!) than these.
