I know some run tracking apps take into account your elevation as you run. Does Zombies, Run do the same? Do the speed of the chasing zombies change if you are running up hill?
From my own experience, and gathered from various posts, the speed of the zombies
requires you to exceed your previous pace (30 second average) by 20%
which implies that the zombies do not care if you're on a hill or not.
Regarding this, I've found that overpasses are particularly dangerous, your speed has to increase a significant amount with a large elevation change working against you.