For a DE style wonder one of the palaces of the Neapolis could sort of potray a transition to a different cultural stage  (which is interesting if the wonder is supposed to unlock phase IV). I think those towns could at least be used for buildings like walls and towers if the Scythians have them (IMO nomad civs could still have access to defensive buildings if they used them, but perhaps later ingame and only through a technology)

It is kind of the case depending on how you look at it :  We could say that units aren't actually pushed, they just look at every neighbor that look too close to them, then they move away from them. Consuming all forces they calculated, tells them where they have to go for this turn. So it's them actually moving away.. Well since all that is a bit some abstraction of physical events probably there are as many way to phrase it as you want.  Edit : I meant is that the pushing range is already some kind of way to communicate to units to move away. But maybe if you wanted to add one that apply only to allies but further then the normal push one, it could be a good idea for example for rams where you want them to push allies but enemy can still block the way. It's a good idea. Edit 2: Now I have regret dropping my initial approach about a forward area in front of units used for charging, that would be maybe a few lines of codes to just make it possible to apply to allies only... I'm glad for the involvement, it shows that this is an interesting topic and that many things will sprout out of it.  In fact, a big highlight of this project is that it will be easy, even from a mod, to plug in forces into UnitMotion. Examples : weather, spells (attractions, repulsion)...

ok, another random guess: Maybe we could use an additional force, where an idle unit clears the path for an allied moving unit, before they are colliding, when it's blocking the way? The blocking unit would just slighty move to the side, but only if there is space available

I see, tangential forces would need friction to act. And I guess including that might cause a bunch of other problems, like units getting quite stuck.

Like a simplification that doesn't account for friction?