A mod maker for Grand Theft Auto V, JulioNIB, created a really interesting mod for the game that imports some of Watch_Dogs' best features while keeping out the rest of the game that was kind of crap. It's a script that adds in some Watch_Dogs style "hacks" into the game. That is to say, you can "hack" street lights to turn green, raise bollards, have ATM machines shoot out money, and more. They even included the means to hack security cameras and blackout portions of the city.

A video of the mod can be seen below. If you like what you see, you can always download the mod for yourself. I cannot personally vouch for the safety of this mod, so use at your own discretion.