Contrary to the title of this post, the world is round. At least some human societies have known this since ancient times. In some circles, referring to one as a “flat-earther” is a reasonably common insult.
In computer games, however, the world is flat, with only a handful of exceptions. This is largely because it is much easier to code a rectangular map than a spherical one. Spheres can actually be pretty hard to draw in 2-dimensions. Common map projections all have considerable distortions.
This makes perfect sense for some games, of course. If the entire game takes place in only a small portion of the world (e.g., a single city, or even one continent), then a small portion of a sphere is more or less flat.
Some games such as the Civilization or Europa Universalis series use a cylindrical map instead of a flat one, which at least lets players go around the world in one direction. This can make sense for games where the technology level is assumed to be low enough as to make the polar regions impassible, and the rest of the surface of the planet is more or less cylindrical.
But a game where the technology is advanced enough to fly long distances or even from one planet to another has no such excuse. If a war spans an entire planet, a rectangular map makes no sense. Yet that’s what we’re usually handed.
Doesn’t anyone know how to make a map with a non-trivial second homology group?
Well yes, actually. Asteroids did in 1979. Some other games have used the same “go off one side of the map and back onto the other” approach. Still, while the world isn’t flat, it certainly isn’t a torus, either.
For a game with frequent loading screens, a somewhat round world wouldn’t actually be that hard to implement. Pick some arbitrary polyhedron, assign a map region to each facet, and make sure that you can get directly from each region to its adjacent ones by going in the appropriate direction. The polyhedron could be something reasonably symmetric, such as a pseudorhombicuboctahedron, or just some arbitrary, irregular shape.
For a seamless world, this would be harder to do, but could still be done. Make the world shaped like an icosahedron, with each facet divided into many triangular tiles. The regions near the vertices would need to either be impassible, or have a loading screen as you approach. Otherwise, as a player approaches an edge, the game effectively folds up the two triangular regions and lets the player pass from one to the next, without even realizing that he’s moved from one triangle to another.
A round world is a small thing, really. It’s not going to make or break a game. But why doesn’t some game leave the ranks of the flat-earthers behind? Why not create a game where the map doesn’t have a canonical “up” direction? Why not make the shape of the map actually fit the lore?