QES
Court Jester
What mechanics do helicopters from Civ use to simulate their ability to fly? As far as I remember its just a flat movement cost. If so we already have several units in FfH that fly.
I see flat movement cost and wings for the art as enough to convince me the creatures fly

THere were fantasy mods for Civ2 - which i loved - and all of those units that could "fly" did so using a mechanic of "cant attack me" or for the helicopter units, it was assumed that the units landed.
For me, flying units would not need to be any more complex than a flat movement rate (like you said), and the ability to cross water and "impassable" terrain. Slap wings on the art and your good to go.
Flavor excuses can be made for why units cannot "fly over" others - just as why assassins and shadows cannot go through tiles occupied by enemey forces without attacking.
Also - the Paradrop function is another fun tool for use of either "teleportation" or flight. At least from Civ2. I know that Im treating this older incarnation with perhaps undue reverance (Zones of control) but I really did have a lot of fun with it.
The 3 possible mechanics I think that wouldnt be horrible for FFH2 would be realatively simple to implement:
Spoiler :
Helicopter flight - Fixed movement rates that cannot be adjusted by roads or other "movement" bonuses; the ability to fly "over" impassable terrain; the ability to fly over water. You add something like -50% against ranged units. And your good to go.
Civ2 Fighter/Bomber Flight - Use this for epic flying creatures. Like - floating cities, or airships (if you like). Specifically, things that stay in the air for LONG periods of time. Essentially make only flying units able to attack these, and require that they revisit cities once and a while. Yes, they can effectively pinch off a tile from movement, as non-flyers couldnt enter the space to attack - but if these are made either into national, world or increadibly expensive units - I dont see a problem. - Make them vulnerable to attack like ships in a harbor when they're in cities so that they dont make invincable cities and your good to go.
Paradrop - This can be used for either teleporting spells or for "temporary" flight for creatures. I love the idea of a spell sphere getting "flight" which would allow a unit to paradrop from their current location to another x squares away. Lots of fun to be had with that. Perhaps it'd also allow the unit to fight flyers with greater effeciency or something.
I know its not perfect - and I know that the vanilla civ system of flight - while more historically accurate cannot suit the needs of a fantasy mod. This is why if we turn to older incarnations of civ - we can find I think, more managable versions.
Another option, that may be at hand - is to give a unit a "non-combat" quality. In this, all flyers are non-combat units. But when they occupy a square with an enemy they'll have an option (read: button) that is effectively an "attack button". Like "build a farm" is a button for a worker. They'll attack the stack as though they'd entered it. If they dont do this - couldn't they pass right through? This was your origional hope. I know.
And I recognize that the main issue here - is that the AI wouldnt understand this very easily - but I'm not sure how the AI works, so i cant give conjecture.
I'd be content with "pretend" flight. But I understand that something worth doing is somethign worth doing well, and I'm content to pine away.
-Qes
EDIT: Question - what units currently employ the helicopter movement? Do i just not use them? Or have never noticed them before?