• Environmental accuracy. The ghosts have a mission to figure out why Mexican rebels are making attacks on American soil. So a lot of the action happens along the US-Mexico border. The developers went to the Texan border area with two panoramic HD cameras to capture 3D-stereo views of the environment.
• Local geography. When the devs watched the videos from the Texan border area, they got ideas. For example, a lot of the buildings at El Paso, Texas, are the same height. So in the game, your team can go across the rooftops. The game has also remained true to the geography around Juarez in Mexico.
  
• Geography and gameplay. Vast gameplay areas and huge maps. So you don't have to go through cuts and transitions to get from one area to the next. Also, gameplay and tactics will have to change based where you are: you have to survive both urban warfare in tight areas (like in the first GRAW game) and desert warfare in open areas (like in the first Ghost Recon game).

Via GameVideos