The Watch Dogs series is part of a genre known as sandbox games. The series combines elements of action, adventure and vehicular gameplay. The player can freely roam the virtual world on foot or by use of vehicles and make use of an array of weapon and mêlée based combat. Illegal activity such as assaulting non-player character civilians and police officers will instigate a proactive and usually lethal response from authoritative figures. In the instance of death, the player will respawn near the area where they were killed.
In each game, the player assumes control of a hacker, who can hack into various electronic devices connected to the fictional ctOS system with their in-game smartphone.[32][33] While most of the abilities granted by ctOS are used to solve puzzles, the player can also use it in free roam at any given time to create chaos and entertain themselves, such as hacking into traffic lights or placing fake evidence against NPCs to have the police arrest them. In each game, the player can level up and unlock new abilities and gadgets. The games incorporate numerous stealth segments, where the player must try to avoid detection by enemies and take them out silently with non-lethal weapons; if the player fails to remain undetected, they may still attempt to kill all remaining enemies, though most times they will find themselves overwhelmed. In Watch Dogs 2, more weapons and hacker gadgets were introduced, such as a taser and a quadcopter.[34]