On a related note, I finally started fleshing out my own homebrew setting for my meatspace D&D game, and the development of Wirld has been fantastic. I started out by saying that days were 16 hours long in Wirld, and that it was quite a bit smaller than Earth.
Using my Astro-mathTM from college, I have found out a few things about this planet.
Radius: 4711 km
Circumference: 29,600 km
Angular Speed at Equator: 1850 kmh
Volume: 4.3795*(10^20) km3
Mass: 2.9716*(10^24)kg
Gravity: 91% Earth
Density: 6.7852 g/cm3
A previous incarnation using the same rotational speed as the Earth (1670km/s) produced a density of 8.2510 g/cm3 with standard Earth gravity.
Earth Density: 5.54 g/cm3, or a bit heavier than Radium on average.
Old Wirld Density: 8.251 g/cm3, which is about the density of Terbium, and heavier than Iron on average. Holy shit that planet would be radioactive. Could explain all the magic, though.
New Wirld Density: 6.7852 g/cm3, almost exactly the density of Praseodymium. Lighter than Iron, though, so I can at least explain it with having a large iron core. That would also explain the relatively small mountain ranges and volcanoes populating the surface, too. Not to mention there's now an explanation for how much precious metal there is to be used as currency.
This was prompted by the party setting forth from the only then-known-to-that-empire continent, at which point I needed to actually draw the rest and figure out how big it is. It turns out that that continent was fairly small in the grand scheme of things. I just have to draw up some more land, build the terrain with what I learned in my geology/meteorology/geography classes, and add civilization.
Hooray for education! Making tabletop games more realistic is a good enough side-effect for me!