ctOS 2.0 is an advanced operating system used in the video game series Watch Dogs. It serves as a central hub for managing and controlling various city infrastructures, including traffic lights, surveillance cameras, and public transportation systems. This system allows players to manipulate the environment to achieve their objectives. In the game, ctOS 2.0 is portrayed as a powerful tool that can enhance urban living but also raises concerns about privacy and security. Players navigate a world where they can hack into this system, highlighting the balance between technological advancement and ethical implications.