According to a report from iGage via 4gamer, the average playtime in Arknights has increased following the Integrated Strategies update. Briefly, Integrated Strategies is the “roguelike” game mode within Arknights, having gone live globally from 14 July 2022. This report is specifically about Japanese players.
The report notes that the 2.5 anniversary event, Invitation to Wine, saw an increase in active users to nearly 350,000 for the week, but it overall remained at around 300,000. As a whole, there was a brief fluctuation but no noticeable increase in active users.
That said, existing users are playing the game for longer. Prior to the addition of the roguelike mode, Arknights already did have a longer than average play time among mobile games at around 45 minutes. This jumped to 72.7 minutes when the mode went live, for a 1.3x increase in play time.
The report also highlights an increase of users playing for over 120 minutes. Before Integrated Strategies, there would be 30,000 at most clocking in over 120 minutes. It has since increased to over 60,000 players following the update. Due to the random nature of the mode and that runs can take roughly an hour to complete, this increase in play time is likely from people who are playing through Integrated Strategies repeatedly.
In sum, while the numbers appear to indicate that new players were not necessarily retained following a celebratory event, the addition of a new game mode was enough to satisfy the existing player base to keep them playing for even longer.