I was thinking the idea of caves with perma darkness was abandonned since a long time, but someone showed me that "caves are not dark as they should be" is still in the bug list.
Hum... If it's just considered a bug, to be honest I hope it won't be fixed soon. Seriously darkness is a level 6 spell, extremely powerful against some nations, extending the effect for free to all caves provinces IMO will have one only effect : make maps with caves unused for balance reasons (or force mapmakers using caves to make them border mountains to avoid the effect).
(so as the only maps I've made have lots of caves I feel concerned
)
Anyway I also find unthematic that darkvisions nations don't have some reasonable advantage in caves. So I have a suggestion (no two in fact) :
-Create an half-darkness state (non magical = non ultra extreme darkness) for caves, with effects comparable to those of a swamp or quagmire spells (or even a little bigger, say -2 att and -4 prec, lowered by darkvision %).
-Or another one (if you find time to implement that) : give caves the default darkness effect, but add specific counter to non magical (caves) darkness (items or spells in the paths the most nations without darkvision have - air&fire I think-, allowing them to be competitive in caves in mid-game, not only one astral high level spell with a high gem cost).
A third option would be to add lots of counters to darkness in general but nations actually using the spell won't like that.
About caves and darkness
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