In Watch Dogs for PS4 The heads-up display elements are visible on-screen. Using the in-game smartphone, players have the ability to view if a civilian is about to be involved in a crime. In the main game, players take control of Aiden Pearce, a vigilante who can hack into various electronic devices tied to the city's central operating system, allowing various methods for the player to solve numerous objectives. The hacking mechanic in the game is performed directly from Aiden's in-game smartphone, which is equipped with multiple applications, namely the "profiler" and the "crime prevention system"; the former allows the player to access information on any citizen in the city, while the latter notifies the player when a crime is likely to occur in the vicinity.
The phone is also equipped with applications that interact directly with the environment around the player; for example, players can hack into NPC's phones to retrieve bank data and steal funds as well as unlock new cars, weapons, and in-game music, or they can hack into traffic lights to cause collisions. Players can also receive information on civilians via augmented reality feeds, providing them with information on demographics, health and potential behaviour. Equipment is also provided by smartphone apps, which can be used to summon cars and weaponry. Players can stop trains, raise security barriers, and black out the entire city and can slow down time to shoot. The game's combat utilises a combination of stealth components.
The game allows the players to use non-lethal attacks and avoid killing anyone should they decide to, except the three main antagonists of the game, Damien Brenks, Lucky Quinn and Delford "Iraq" Wade. The hacking element of the game can also be used in combat situations to eliminate opponents, create diversions, or create cover. It can also be used as a stealth tool to sneak past guards. In combat, auto-aim and a cover system are available as assistance against enemies. If players take damage, their health meter will gradually regenerate. If players commit crimes while playing, the police may respond, as indicated by a meter in the head-up display. On the meter, the displayed levels indicate the amount of attention the crime demands.