To interact with any object or person in the game you will use a three icon symbol that appears on any object you can highlight on mouse over. Simply hold the left mouse button pressed for about one second when any object is highlighted like this desk. You can select the required action by holding the mouse button pressed and by releasing it over the icon you want to select.

The icons have the following functions:

Talk: use this icon to communicate with people. You will collect useful information and you will gain accomplices you can use in your plans later in the game.