I feel like a number of those proposed effects are going back into that "Don't know where north is until Compass" territory again.
It's kind of the wrong way to approach design for games, imo.
You think of an effect that relates heavily to its real life function or purpose,
without thinking about whether it would be fun in an actual game, you know.
The number one thing I always ask myself is: "Would I play this, or enjoy this mechanic?"
Ben:
It's too convoluted. If the Great Wall had that effect, I think first-time players would get frustrated wondering why killing those Barbs were sometimes easy,
and sometimes their defenders would just get insta-gibbed. It's not intuitive.
No one expects to lose their bonus just because a unit attacked them from 1W as opposed to 1N.
Tigranes:
Land forts are a massive fail even in base BtS in terms of fun design.
Chokes aren't prevalent on most maps and a fort is easily circumvented by, walking around it or landing troops on the other side, like in the case with the Sinai or with the Istanbul choke.
Assaulting a fort gets you nothing of value except a lot of wasted blood and treasure.
You don't deny the opponent anything and you lose a lot in the process; not to mention the trouble is easily avoided.
Before the changes that allowed you to access resources on islands in your BFC with a regular improvement, Forts had the function to help a player obtain them.
xcept they couldn't be worked for yields, or good yields at least. And Forts as canals are simply amazing.
It's that kind of useful functionality that Forts need more of if you want to make them viable enough to base a Wonder around.
Your idea is making me think though, about Civ5 citadels and what they do right:
They actually make people care about their presence. No one wants to take chip damage constantly from being in the vicinity.
If the Great Wall is to have any change, (I wouldn't prefer it)
An effect that would be superb, simple and fun to use, would be if the Great Wall produced the Russian UP effect;
to represent the information relay the Wall was used for by making the invaders vulnerable to attrition and attacks from all sides by defenders who know the land better.
It's still generally weak as a defensive effect, but that's a result of DoC being an up-tempo game.
citis:
If you really want to get into semantics about history. China had never ever had to worry about invasions from the south after the pacification and Sinification of the Baiyue.
Only in the modern era with the French.The Tibetan invasion was largely a one time thing and didn't achieve many substantial aims.
My point is, it's really inconsequential that the effect also happens to work on Barbs coming from Indochina and the Tibetan plateau.
Like really, it's a weird thing to get hung up on.