@soundmud, thanks for your aclarations about ford.
So, I misspelled a word; I didn't want ask to you about the highgrounds: I want to ask to you about airground_types. If are you planing to parametizing them, or only have them harcoded.
Ground, air, water, etc
The idea of "non-air" squares are really awesome, for create strech mountain paths, or high mountains that any can't pass between them, or caves where only grounded units can pass. sounds a good idea.
About the big bridges sounds good, but... the easy mode, is enable the option of have a square with two airgrounds types, (water and ground) instead of create a sub-square; this second option make harder the problem, because probabli move to you of have a 3d map with a squares with three coordinates and that solution sounds very complicated.
About bridges and roads... is a idea that you've to think slowly...
The purpose of a bridge is simple, but... ¿how it will works? it blocks the water course and impide the pass of the water units turning the water square into a ground square? or...
O, i have it!
If you add a skill that enable the modification the airground of an square (with a range deppending the configuration) a bridge is only a building, with a gate skill, that change (or simply add) the airground type of the connecting squares with the ground.
With that, you kill two (or more) things with one shot.
Add bridges, and add a skill that
can modify with adding, removing, or totalli changing the airground type of a square, of range of squares.
With that you can add infested airgrounds, add some skills that for example add mud airground to a square slowering enemi units, etc.
taking the problem for that angle will be a interesting option.
Well, thanks for all soundmud.