Create own turn based strategy game? (like Advance Wars, FF Tactics)

Are there any tools out there that allow you to make your own turn-based strategy games in the vein of Advance Wars or Final Fantasy Tactics? I know lots of these games allow you to create your own maps, but I also want to create units. I'd be open to any platform, but I'm assuming PC/Mac is more likely, so I posted here.

There is a Game Development Thread here on CAG and that is probably a good place to start.