The HITMAN servers are down for maintenance in preparation of releasing Episode Three: Marrakesh.
When the maintenance period is over, which is expected to be at 13:00 CEST, a game update will begin rolling out. When that update is installed, Marrakesh will be available to play in-game.
Updated Release Time for Marrakesh: 13:00 CEST
(Previously communicated time was 18:00 CEST)
Look here for the time in your region: http://www.timeanddate.com/worldclock/fixedtime.html?msg=HITMAN+-+Episode+Three%3A+Marrakesh+Release+Time&iso=20160531T13&p1=69