This looks like an interesting topic, but it seems to have died, due to an all to common problem, worrying too much about the graphics.

{MSX}, have you already started on this game?

If not, here's some of my opinions:

I would suggest 2d, Iso, or even squared top down tiles.
Being turn based, 1 on 1 multiplayer is rather simple, since you need not worry about lag, etc.
Single player is a bit harder, in my opinion, cos you have to create AI.

Anyone still interested in breathing life into this idea?
I can help with coding, 3d and 2d graphics.