I say this only because in the books, there were many places in the desert that was just too much of a pain to get to.
Like what?
Consider the Arrakis mapscript. The places on the planet that are too much of a pain to get to are off-map; the map basically represents only the planet's arctic circle.
There aren't really any places inaccessible to thopters, but it takes time and fuel and mostly there isn't any value in going there (on earth, you *could* go out into the middle of the Sahara desert.... but why would you?).
And thopter can still only move a few tiles at a tile, so it is a pain for them to go long distances.
And there are storms that can destroy thopters if they get caught in them.
As for Fremen scouts, there isn't really anywhere the Fremen can't go; they can ride worms all the way from the north pole to the palmeries of the south pole (20 thumpers).
I would think that if it's possible to code, would be that after 2 turns or so outside your cultural boundaries, units start taking damage every turn
I think this would destroy the AI. The AI, on two separate islands, has to cross some open terrain to get to you, but their entire strike force gets damaged or destroyed on the way over because they don't understand that areas outside culture cause damage?
That sounds really bad for gameplay.
Or: you conquer an enemy city, it goes into revolt, and loses its cultural radius - so now any units in the surrounding tiles start taking damage?
I mean I get the impression (it's implied) that when the Harkonen go after Muad'Dib's deep desert seitch, that they got the Guild to drop their troops via orbital insertion instead of actually flying all that way (which would most likely be detected)
The Harkonnen don't; its the Sardaukar. And yes, its implied that its orbital insertion, but of course, if you have most of your forces in space, why wouldn't you just land right there?
That doesn't mean that you couldn't get there by flying, it just means its easier not to.
And again, all those central regions with the worst storms are not represented on the Arrakis map.
Again the books point out that there was areas of Arrakis that were unknown because the Fremen bribed the Guild to give inaccurate satellite pictures.
Well, they bribed the guild to not let anyone put satellites up. So nobody knew that they should bother trying to explore there. It doesn't mean they couldn't. And again, those regions are off-map.
So by putting limits on scouts, you force players to have to do 'leap-frog' sort of scouting
Why is this a desirable goal? Scouting isn't really that important in this game.
second Fremen civ mentioned in another forum
We removed the second Fremen civ a while back.
Also, the value of colonizing an area is primarily determined by its water resources. There is no gain in colonzing small rocks in the desert with no water, even for Fremen.
Also another quick observation is perhaps the code from FF/Orbis could be used to fiddle around with the Goblin Fort and turn it into a Smuggler's Cove where you could 'buy' units
Why? Nobody really hires smugglers as mercenaries in any of the Dune books, and we already have a cash-for-units mechanic with the Homeworld screen.