The duration of a game usually depends on the way the gamers play and especially on the level of difficulty at which they prefer to play and which can therefore slow down the experience.
Now, if you are wondering how long will it take you to complete the Gotham Knights story well, according to the Radiotimes, it would take 20 hours to reach the credits of the game. This estimate is not unrealistic since the title only has 8 chapters. Of course, the experience can last much longer since if you want to finish the game 100%, you will have to do all the side quests and all the achievements, collectibles as specified by the HowLongtoBeat site.
Gotham Knights will be available to play from October 21 on PC, PS5, Xbox Series X and Xbox Series.