In an official post in the Steam Forums, Hitman Community Manager Travis Barbour explained the new live modes being introduced with the game.

The Elusive Targets are characters, who are added to pre-existing levels. They have their own briefing video, backstory and reason to be in the level. They are not marked on the map and can’t be spotted via Instinct mode. You need to hunt them down, using clues from the briefing and the photo you have got. The most exciting thing about them is that you only got one chance to eliminate them, because there are no game saves or replays available. If something goes wrong, you have to deal with it, if the target escapes then you are screwed.

IO Interactive will reward you for completing several Elusive Target through a season. Mastering these tough challenges grants you access to signature suits and gloves from previous games and versions from the new one.

Travis Barbour describes Escalation Mode as challenges, which get harder step by step. As an example, the task could be to eliminate your target with a sabre. The second stage could be to eliminate your target with a sabre whilst dressed as a waiter and removing any security camera recordings within two minutes. The developers are able to change where the security cameras are and also add additional traps to the locations, such as laser trip-wire explosives. You can replay each challenge with its five stages as often as you want to climb the leaderboards, but save games are disabled here, as well.

Elusive Targets and Escalation Modes are planned to be added between the location updates of the game.

Contracts Mode is back and again you can create challenges for other players after you mastered them all by yourself first. Used a funny outfit with an unusual weapon in a tricky situation while killing your target? Find out if others are as good as you. If your contract is very entertaining or challenging, it could possibly be featured by IO and suggested to other players when they start the game.

IO Interactive is looking into other Live Challenges, as well. Travis Barbour describes them as “an homage to some of the more elaborate, amusing, difficult or creative feats that we see our players complete.” These challenges could be inspired by the community like the “Hammer Time”. It was a player livestream from the game’s beta, where every guard was killed with just a hammer.

Source: SteamCommunity.com – What is the “Live” component of HITMAN?