Watch Dogs senior director Dominic Guay has told Polygon that roughly ninety-five percent of missions in the game can be completed using the stealth route, rather than using weapons. Guay says it’s entirely down to players how they decide to approach the game and that there are very few missions that will force the player to take the weapons route.
“About 95% of missions you can completely stealth through, or flee or chase without having to shoot. So it’s really player choice-driven. There are a very few, very limited amount of missions that will force you to kill people.”