My understanding is Space Engineers takes the "blocky sphere" approach mentioned early in the post, works around the "walk along its surface" part of the problem by making gravity direction point towards a fixed point, and bypasses the "trying to build 'upward'" part of it by not allowing voxel construction. It doesn't use a quad-sphere at all.
Eco: Global Survival (https://play.eco/) bypassed the distortion problem entirely by using an undistorted flat voxel grid, but rendering the globe view as a torisphere.
It still has the tradeoff of making travel close to the center take longer than it should on a sphere (worked around by limiting diggable height), but i find it a more elegant solution.
It's an elegant rendering trick, but if their worlds are represented as a torus, then I expect this would make rotation on a spherical globe view unintuitive.
One example of this: I would expect each location would not have a single antipode (opposite coordinate) but would instead have three. If you were to start at location A, rotate travel 180 degrees along the latitudinal axis to location B, then 180 degrees around the longitudinal axis... on a sphere you would expect to be back at location A, albeit upside down. But on a torus, you are in a completely different location, which is the 'C' antipode. Rotating 180 degrees latitudinally from here will bring you to point D, the last of the antipode set.
I don't find it to be a problem as planning a route from A to B isn't done by looking directly for it, but by subconsciously referring to and plotting a path through landmarks along the way that aren't close to antipodal.
One of the worlds i played on had road planning from the start and a set of roadways covering the entire world in a 4x4 square grid. Pathing to point D was just a matter of going 2 blocks in one direction, and 2 blocks in an orthogonal to it.
In a world without such roadways, you'd look for landmarks such as oceans and continents instead.
Ultimately, you don't care if somewhere is antipodal or not because you never see the antipodes to where the globe is currently looking at without rotating the globe.
It's 10% of natural mercury. you're looking into separating it cheaply instead, or at least hope the other naturally occuring isotopes don't cause too many problems.
What's with the 12-34-21-33 loop shown on Concorde's st70 path as shown on OP's article? You'd expect it to avoid intersecting routes in a final answer to a given problem.
