In Killer7, you take on the role of a group of seven elite assassins, led by Harman Smith, who relies on Garcian Smith and the other assassins to do most of the dirty work. You can switch between them at almost any time, so if you feel like some challenge or puzzle can be better solved with one or another, you can just change out to a different one quickly.
Source: N4G PC Killer7 review – ChristCenteredGamer