Here's the idea: it would be really interesting to see various global events, so the war is a bit different every now and then. The ones that came up to my mind would be changes in reinforce cost of certain units (perhaps like a drought or sth for negative effect and good weather conditions for positive effect?), also cost of defences, and perhaps sth like "harsh weather" (makes battles resolve quicker, units want to get out of the sandstorm or whatever).
Perhaps it could also vary on resources? Like "each faction gets X for every Y resource they have". Like a palisade in every battle for every wood resource.
Let's discuss.
