I was expecting the same game, but from paceman's pov. so you'd see a small line for the dot and a bigger line behind it for the ghost. After thinking about it, I think the game would function the exact same as the lined one, just a drastically different perspective.

If Pac-Man and the ghost positions are on the x axis, what is the y axis used for?

It's a 2D game with one axis of movement. Technically correct and all that.