Those who push through the story as quickly as possible are looking at about eight to 10 hours to complete Detroit: Become Human. However, those who take a little bit more time exploring the environment and looking for collectibles can expect to add another hour or two to their initial playthrough.
With three times the branching paths as Heavy Rain, Quantic Dream clearly intends Detroit: Become Human to be a game that people play through multiple times. According to materials provided by Quantic Dream, going back through the game to see every possible outcome is going to up the playtime to about 40 hours, so completionists should have no problem getting their money's worth.
Anyone who wants to earn the Platinum trophy will likely need to play through the game more than once, as players are given trophies for different possible outcomes that aren't all possible on the same playthrough. This should encourage people to replay the story from the beginning, or at least return to specific scenes, to push the plot in different directions and earn some trophies in the process.
All things considered, Detroit: Become Human is actually somewhat lengthy for a game of its nature. The numerous branching paths, the massive 2,000 page script, and the collectibles hidden in the environment all add up to give Detroit much more replayability than is typical of a game like this. As previously stated, players who want to play through the story once and be done are looking at about eight to 10 hours, but those who want to complete it fully can expect to spend nearly 40 hours with the game, if Quantic Dream's estimations are correct.
Detroit: Become Human launches on May 25, exclusively for PlayStation 4.