I realise FT allows the creation of a planar synthetic world, but I was wondering about a synthetic ring world. I understand what you are saying about resolution limitations, but if I went with a smaller ring world, how would I go about joining up the far left and right edges of the map with no seam?

My purpose for varying the sunlight was to try and force some sort of seasonal variation, but as you pointed out the angle would be constant which would defeat the purpose. I suppose it could have a 'wobble'. Any ideas for forcing seasonal variation?

As far as gravity goes I figure there are two methods I could use. The first would be rotation, however depending upon the rotational speeds required for 1 gravity, I can imagine some fierce winds rushing around the ring. The second option would be some kind of super science/magic artificial gravity system.