Quote Originally Posted by Falconius View Post
Tidal locking for those of us who have to look it up How would such a construction affect the ocean tides? and also how would it affect the day night scale?
Since tides are caused by the shifting affect of gravity between two objects, and the world doesn't move relative to the planet, I don't think there would be (oceanic) tides. I'm no astro-physicist though, so I could be totally wrong. HOWEVER, tidal heating would be a MAJOR impact. One would expect significantly greater geo-thermal energy availability as a result of the tidal acceleration, leading to a) a "bulge" in the world that makes it an ellipsoid rather than a sphere (Earth is actually slightly ellipsoidal); b) the potential for lots of volcanos, geysers, etc.; and c) generally a warmer world than would be expected if it were just orbiting the star normally at the distance of the planet.

Other differences would include:
- Frequent radiation storms from the gas giant. Since it isn't a barren rock, the world must have a strong electro-magnetic (or in this case magical?!) field protecting it from this radiation. The practical affect is that aurora would be spectacular.
- One side of the world would always face the parent planet. The other side would never see it. (imagine the cultural differences that might create)
- A "day" would be equal to the time it takes the world to orbit the planet. That would typically mean a day longer than 24 hours, but we could fudge the number, particularly if magic is involved.
- Depending on orbital alignments, the side that faces the planet might get frequent eclipses. This might influence climate. It would certainly get additional light some of the time, due to the light from the star reflecting off of the gas giant.

If you want some crazy details, have a look at these papers:
http://arxiv.org/ftp/arxiv/papers/1209/1209.5323.pdf
http://arxiv.org/pdf/1210.5172v1.pdf

If there's more interest in the binary system model, I can lay out the (mostly much less severe) possible impacts of that as well...

With the gunpowder/greek fire thing I think we are getting a bit too involved in the detail as this is unlikely to have significant effect on the maps whatever or not we go overboard. Besides the overboard things like a sea of fire (would be cool in any case in my opinion). There isn't so much to worry about. (guns though do have significant impact on maps)
Those were just examples of the "tech level" limitations that I think are critical to defining the limiting parameters of the world. Reasonable limits on certain realms, including weapons, but also transport types, energy sources, magical power sources (and anything else that would completely change the world by its presence) help keep the world in balance. But you're right. Unless it has global geo-political/cultural ramifications, it can undoubtedly wait until later to determine/resolve.