You might want something that works a bit like Dark Side points? You can gain a benefit with an action that's in accord with the Curse in your locality (or the one you grew up in, I suppose), but you gain a curse point, pushing you towards the next threshold.Character based: The curses can take many forms according to the actions of the characters.... There would be a number of thresholds (something like 3-5). When you pass a threshold something with the prominent curse occurs. ...
I am not sure how someone can gain these curse points. I can see curse points could be gained in ancient ruins/temples where the presence of the old gods were more prominent. But where else and which circumstances would occur in order to gain curse points?
It makes some sense to break it out by caster vs non-caster, and divine caster vs others. Casters and non-casters simply do things differently. Divine casters might have greater vulnerability or resistance depending on how the new gods stack up to the lingering influence of the old.Actually I am not sure if like the "character-class" based curses.