Aiden in the Announcement Demo. How does he get to his target? He causes a multi-car pileup, and rescues a civilian trapped in the aftermath before tearing through the target's goons and eliminating him.
The main game adds to this- Aidan's target was just a name in the demo? Here? He's the ringleader of a human trafficking ring (Many players reported feeling horrified by what they saw there), and you're allowed to kill the SOB in any way you want.
Aiden getting himself arrested. He just walks into the Jail where the witness for the gang massacre is, and pulls out his gun and just hands it over to the cops. The entire thing progressed so quick without any fuss. And then he almost as easily breaks out, either by gunning down almost every dirty cop in the jail or just being really sneaky. It goes to show how efficient Aiden and Jordi are when they work together.
The existence of The Bunker is awesomeness in itself. Clara certainly thinks so. It might reminds you of your secret base childhood fantasy a bit.
How Aiden kills Lucky Quinn at the climax of the game. He thinks he's invincible since none of Aiden's weapons (not even six consecutive auto-shotgun blasts, tried it) can penetrate his safe room, and he even made most of the safe room hack-proof. So Aiden just hacks HIM to death. To elaborate, Lucky gloats about how he is invincible, considering that he killed people more badass than Aiden, and suddenly you get a prompt to open up the profiler. The profiler and clues in the room indicate that Lucky has a failing heart, which is normal for an old man... and then you get one evil moment to realize that HIS PACEMAKER IS CONNECTED TO ctOS. Enjoy.
Aidan taking down the Viceroys at "the bricks" with I.E.D.s while "Wu Tang Clan's" "C.R.E.A.M. is playing. Bonus points in that if you know how to make Proximity Charges, you can have twice the boom.
A minor one can be found in one of the privacy invasions: A woman is thorughly chewing out an obnoxious radio personality for his homophobic comments, saying how she loves her daughter(who is a lesbian) and when he gives the "it's a free country" excuse, she counters by saying that "hate speech" and "ignorance" is not a right and then tells him that a person(the host) who hangs out at a crackhouse has no room to judge others.
One can, depending on the area the gang hideout is in, get in a vehicle and run over the gang members, instead of going into shootouts.