It is not a sphere, just the usual Pacman map displayed with a cool projection. A sphere cannot be tiled with squares like this (a beautiful math fact). Also the surface of a sphere is non-Euclidean so the angles on it work differently. If you made a loop and returned to your original location, the world would be rotated because of this (another beautiful math fact). Non-Euclidean geometry produces a very different gameplay.
There are some games in truly non-Euclidean (spherical and hyperbolic) variants, but there is no (publicly available) Pacman yet I think. There are some a bit like Pacman but still far away.