Howdy!
There's a few variants of tactics systems from the past. Basil did a tactics system (not FFTish, though)
Dirty tactics 2.0 (patch)
I did, like two years ago and in winv2, a Shining Force / FFT style demo called
Hero Rancher, and although the battle system's logic never got in, the battle system's pathfinding and targetting systems were. It may be worth checking out, but I have hazy and dim memories of the whole venture.
There have been others, I think, but these stand out in my mind.