I was responsible for everything to do with the planet and control system. The camera was designed to orbit the planet in a smooth fashion, zooming out slightly as it spins as though thrown out by inertia, then zooming in as the camera comes to rest. I used raycasting for touch events to determine which city the player was attempting to click on.
I also took a great deal of care to make the planet look as beautiful as possible, within the limitations of low-end mobile devices. This included atmospheric scattering and dramatic sunset effects using scripted billboards. The planet also featured city lights on the night side and a moving cloud layer.
The paths between cities had to be rendered as great circle arcs. I wrote the code for calculating and drawing these paths on the planet.