Watch Dogs launches just hours from now, so you'd better get the companion app, ctOS Mobile. ctOS Mobile is available for both iOS and Android, is free, has no microtransactions and doesn't require players to own Watch Dogs, either.
Ubisoft's ctOS Mobile app includes two modes, the first is Race - where the distance between checkpoints are short for gamers who have GPS enabled. The second is Free Ride, which opens up the distance of the checkpoints and turns the GPS off. As Watch Dogs gamers reach the checkpoints, they gain time, with gamers sitting on their mobile devices using the ctOS Mobile app can hack the city through a top-down view.
Using the mobile app, they can trigger barricades, set off explosions, call in assists from helicopter-stationed snipers, and the police. ctOS Mobile players have the task of stopping the gamers in Watch Dogs, and if they assist, they win. Just don't download the torrent copy of Watch Dogs, folks.