aramis erak
Legend
Not quite, but adjacent...In essence this seems so broad as to encompass the vast majority of RPG design, which may be your point.
Most games do not try to avoid exceptions.
FATE Accelerated is about as close as any I've seen. Everything is done using stats and assets.
Cortex Prime comes pretty close, as does 2d20 Dune...
but my actual point is that the mechanically interesting parts of a design are usually exception based.
Agreed.This is why I flagged the board game Cosmic Encounter, because it is probably the clearest example ever of a pure exception based design. Simple core rules, and everything unique about a given alien is simply a description of how it can break the rules. Later sets diluted that in a sense by adding additional subsystems, but in all cases every player gets to use all of them, they just provide added stuff to create exceptions in. This illustrates the complexity increase path for a system like that.
The thing about D&D 4E that appealed to me was that essentially, there were only a dozen total exception mechanics; they were reflavored extensively using a narrative limitation.
The thing about D&D 5E that annoys me is there are at least 2 dozen exception types, and by 8th level characters, I can't keep track of who can do what when as a GM...
2d20 Dune and STA have several key exception mechanics reused widely:
if (condition == True):
— reroll 1d20
— reroll (score) d20s
— gain extra momentum (spendable bonus successes)
— reduce the momentum/threat cost for ___.
— ignore some existing trait.
— Give an extra trait (general trait, advantage, complication, or value)
— allow using a different ability than standard.
STA also adds:
— reroll some d6's in a damage/progress roll
— add extra qualities to a given action
— add extra Effects to a given action
The core mechanics include the Trait...
If trait applies:
— making it harder: D+1
— Making it easier: D-1
— making it impossible: D=∞
— making the impossible possible (D set by GM)
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About a dozen for STA.
One of the key elements is that the major metacurrency, Determination, normally cannot be spent. (That's its default condition.)
Several mechanics are supersets or subsets thereof:
STA Values are traits that specifically do making the impossible possible: you have to invoke a Value to spend Determination. Official answers noted that they're still traits, and can provide the usual trait benefits if not used for Determination spends.
In both, Advantages are traits that only apply when...
— Making it easier: D-1
— making the impossible possible (D set by GM)
...and Complications are traits that only apply when...
— making it harder: D+1
— making it impossible: D=∞
Not as straightforward as Fate, especially FAE, but still on the low number of exception types.