Originally Posted by
Hai-Etlik
Is this on a spherical planet? If so, this gets complicated. Projection from a sphere to a flat map causes distortion. You can change the kind of distortion and where it it, but you can't eliminate it. If you don't want distortion, you need a real 3D globe.
So for any particular extent (area covered by a map) you should pick a projection that minimizes distortion within that extent at the expense of areas outside it. Unless everything you are doing is at a fairly large scale (Neighbourhood to whole city isn't a problem for instance) significant changes of extent require changes of projection in order to keep distortion minimal for that map.
There is a trick that sort of lets you cheat this, and is how zoomable web maps like Google Maps and Open Street Map work. If you use the Normal Mercator projection, then when you zoom in to large scale, you get something that works reasonably well (you just need to adjust linear scale based on latitude). This cheating breaks down in between at medium scales though, particularly for big shapes at high latitudes. Canada for instance looks very wrong. Bear in mind that Normal Mercator has weaknesses as a reference map, in particular it can never show the whole planet as the poles end up infinitely far away and have to be chopped off. A square Mercator map centred on the equator chops off the poles a bit past 80 degrees.
If your world is flat, then you can zoom and crop without worrying about projections. You do have to worry about other things like avoiding all the concepts that we take for granted from living on a sphere (Latitude and longitude, celestial navigiation (Using the stars to figure out your location), seasons, climate varying with latitude (As there is no latitude), the horizon, being able to see further by getting higher, compasses) Some of those can be fixed by applying appropriate magic (Done right this could aid in making the world seem fantastic and magical) but it's something you need to work out.
A "large continent" is probably the most inconvenient thing to work with in terms of projections. It's big enough to make sure you have significant distortion problems, but it's not a full planet so you can't just use an existing world optimized projection.