[advice request] Animating the curve-deformed chain for export to Unity

Need a piece of advice on animating a curve-deformed object. I feel batshit braindead for this task already.

I have a chain that’s supposed to be moving to and fro along a curve; the chain is parented to an Empty object which is moving, in turn, along the Y axis, so in fact no Transform parameters of the chain itself are affected.

I need to export this to Unity 5 which, as far as I know, applies modifiers and gives no dung about curve deformations, etc (it will just apply all modifiers).

Which, I understand, means that I need to have the chain itself animated, so that it is properly deformed (shape keys?) at the proper keyframes.

Please, give me a hint on a workflow here!

Thank you!

I think shape keys will not work because they are linear interpolated (Vertecies takes all time the shortest distance between old and new position).I would say you need a rig and I guess the workflow is as follow.
First amature for the rig control and second amature for the deformation and bake process which should exportable for unity. Use the new depsgraph to avoid dependency cycles.

-create a curve for your chain (not more than 3 handles)
-create hook bones for the curve handles (first amature)
-create spline ik bones for the curve (second amature)
-create copy transform bones for each spline ik bone (first amature or create a third one)
-create weights for the chain from the copy transform bones.
-animate the hook bones
-select and bake the animation to the copy transform bones

To get the Y rotation just use the first and last hook bone and give all spline ik bones a copy rotation from these two hook bones. Change the influence to get smooth transition.

Or use Tokas setup with a second curve and emptys and lock track for the spline ik bones.

I wish you good luck