I am not sure if this is what your looking for, but it might be something to take a look at, as it has a map editor I think. (It might also be thats it is not the graphics or look that your after)
http://en.wikipedia.org/wiki/Elemental:_War_of_Magic
tom didn't fancy that. wrong scale, apparently. it does have a 3d map editor.
thing with it... is that if you really zoom out.. you'll get a cloth map... heh.
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it's got biggish squares too and i haven't figured out how to place buildings... XD
