Thought this would be interesting for you all to take a look at:
http://io9.com/what-would-the-earth-be-like-if-it-was-the-shape-of-a-d-1515700296 (http://io9.com/what-would-the-earth-be-like-if-it-was-the-shape-of-a-d-1515700296)
It goes into the physics of a torus shaped world and seasons and whatnot. Most interesting thing, in my opinion: gravity would not be consistent across the entire world, and the orbit of a moon would get crazy wonky.
I'm gonna use this.