Okay most of the stuff here may be known, maybe just speculation on my part, or things you may have missed, contribute and let us break down the demo
-- It looks like it will be an open world game, probably with side quests too.
-- you can hack into any NPC with an electronic device
-- Jam Communication is a function that makes you stop any electronic device around, to make something like a panic attack or a distraction.
-- Aiden Pearce it seems he is known for some of the people, why remains unknown, but it can't be good.
-- There is a Search Function for him to identify his targets.
-- Violence Meter I believe it is something like the detection one in hitman, as long as you are keeping it low nothing will happen, but when it reaches the top they will probably attack.
-- There are non lethal takedowns.
-- 2 other functions are Controlling Traffic Light and or Controlling Train.
-- you can conceal yourself by a bandana and conceal your gun by hiding it behind your back
-- There is a Slo-Mo system and Cover system.
-- you can slide over cover and shoot at the same time.
-- There is Regenerative Health System.
-- There are a variety of weapons between hand gun and assault rifles.
-- you can ride cars and use the Bridge function to raise bridges.
-- There are Police chases with Helicopters too.
-- Intrusion detected, probably your device can be hacked.
-- Aiden Pearce is probably not the only playable character, and since the other character have access to the roof there may be some sort of free running.
-- There are around 7 more names beside Pearce and Bixxel .
If i missed something, add it, keep on it, we may be able to discover more