Battles between alien craft and X-COM crafts will cause damage to buildings and pedestrians which will cause tempers to flare and not always against the aliens. Many people are concerned that the game will be too limited with only one city to play in. And while this seems true when one looks at the prior game play, the current game will have a level of city detail that will have many, many buildings, parks, organizations, and factions with a high level of detail. This level of detail is why the game is limited to one city. The entire world would just be too large, all things considered.
Research is divided into three arms including biological, mechanical, and quantum.
A medical bay is required to heal injured troopers. Training areas and Psi-gyms will allow agents to improve their proficiencies. At the highest difficulty level, the city is huge. The largest city has criminal gangs, cults, the police, and various earth factions that are fighting each other. This unrest is exploited by the aliens making your job more difficult.