Civilization Revolution (DS – reviewed, PS3, 360) » Bottom Screen
The bottom screen is where the majority of the game takes place.
The bottom screen is where everything really happens. It is possible to control the whole game using solely the touch screen or the buttons and any mix of the two. Both methods work well and due to the amount of overlap it always felt intuitive to me.
Thought times the small screen does get cluttered its never too hard to follow as the game tracks the action well. City ‘jump’ keys also means you are rarely more than four clicks away from where you want to be as your empire never overly expansive.

