Will dwarf fortress have seamless terrain? Like,if you walk to the west long enough,and swim across the seas,you will end up back where you started? The map would not need to be mapped on a sphere.Just a seamless texture.It would add very much to the immersion.
Following on from the earlier reply, it's a difficult problem in general to map a spherical world using a square grid, because of the non-Euclidian nature of sphere geometry.
If you are at any point on the Earth* and you travel a mile north, then a mile east, then a mile south, then a mile west, you will not be in the same position you started. Close to the equator and the difference is small enough in the human/dwarf scale that it can be fudged, but as you move towards either pole and it becomes so pronounced that a square grid starts to either be stupidly unrealistic or becomes confusing to a player/navigator.
The standard game solutions are either to use a toroidal (do[ugh]nut shaped) universe, where you go off the left of the map and appear at the right, and going off the top of the map you appear at the bottom, or you make the poles impassable and then reduce the problem to mapping a cylinder, which is much easier. A more 'sphere-like' effect can be done by mapping the world as a 20-triangular-sided icosahedron**, but then you need to map fundamentally as hexagons, with 20 pentagons dotted around the globe that really screw things up - very hard to map to a grid, but a good way if you have a 3D graphic engine. Toady's other option, where travelling north off the polar edge of a cylindrical world leaves the player travelling south at a point 180 degrees of longitude away, is liable to leave players very confused if there is any kind of in-game compass which would suddenly switch direction - although in theory this would happen on Earth when you travelled over the magnetic pole.
The problem boils down to the fact that at some point with any spherical model, you will have grid squares that behave very weirdly, so in a game the idea is to hide these weird squares from the player so that they don't detract from the experience. The 'impassable poles' cylinder is quite a sufficient model*** for most games (Sid Meier has done OK so far...) especially in a game where 99.99% of the world's inhabitants would die at that sort of exposure. Of course, in a fantasy realm, where magical heating/protection is available, you need something else - quite often the north and south poles are the locations of the homes of the gods (good and evil opposites perhaps) where mortals can be dealt with quickly......
Sorry to be so off-topic for the FotF thread, just wanted to pontificate on a favourite subject!
* other than half a mile south of the equator, or some specific latitudes near the poles
** or if you're really clever, a multiply-stellated icosahedron
*** in DF, because the grid mechanism is largely forced on the game by the choice of graphical engine, a really good compromise is to use an impassable poles cylinder and fractional time, then either make east-west movement take less time (by a factor of the cosine of the latitude) or additionally make the north-south grid similarly compressed to avoid confusing the player. So moving 1 square would take say 1.00 seconds at the equator, but 0.71 seconds at the 45th parallel. Since the player is essentially limited to walking speed for large-scale movement, the change in the compression effect wouldn't be noticable during gameplay.