re: Official Watch Dogs Discussion Thread (PC/Xbone/PS4/Xbox360/PS3)

Other players will appear as random npc characters and attempt to hack you. They install a backdoor and then find a place to hide and begin the hack. Your player uses the profiler to try and find the other player and stop the hack. As the hack progresses, the search zone narrows to help the victim. If/when discovered the attacking player has to escape. Points are awarded towards a multi-player specific skill tree upon escape/hack/death. It's not a pass/fail system so partially hacking another player and escaping is worth more than dying.