This is interesting. I agree that it definitely 'feels' like some resources are civ dependant. Is there any real evidence for this however?
I'm not sure there's evidence supporting or denouncing it. (Glancing over the scripts, it doesn't appear there's any consideration for UU resources.)
I think it's a matter of perception. After all, if you're Persia, do you really care if Copper is 20 tiles away when Horses are in Persepolis' BFC? On the contrary when playing Greece, do you care about the Horses in Athens' BFC when Copper is 20 tiles away?
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It depends on the map script and the settings used to generate the map.
For example, how often do you see Marble on anything other than Plains or Tundra ... or Stone not on Plains or Desert? So what happens with a Cold or Arid climate setting? (That's right! Marble goes up and Stone goes down for Cold while Marble goes down and Stone goes up for Arid!)
Similarly, it's not uncommon in Hemispheres to see Stone on one side of the globe and Marble on the other (I've also witnessed this in Continents and B/M&S).
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That being said, I agree with 85/45 ... Marble or Stone appear within reach in ~80% of my games, while both appear in ~40%. Either appears in the BFC ~5%. Both in the BFC is a fluke.
-- my 2
