Developer Mountain Contour is releasing the version 1.3 update, titled "Sketches of Lost Heirlooms," for Arknights: Endfield on June 5, 2026 [1].
This rollout marks a significant content expansion for the free-to-play 3D RPG. Regular updates are essential for maintaining player engagement in the competitive live-service gaming market, where consistent feature additions drive retention.
The global launch is scheduled for June 5, 2026 [1]. However, players in certain regions may receive the update as early as June 4, 2026, depending on their specific time zone [2]. This variance is common for global server deployments where maintenance windows overlap different international dates.
Version 1.3 [2] is designed to deliver new content and features to the player base as part of the game's standard update cycle. The update will be deployed worldwide via the official game servers.
While the specific contents of the "Sketches of Lost Heirlooms" update have not been detailed in the release announcements, the version number 1.3 [2] suggests a substantial iteration over previous builds. The deployment is being managed by the developer, Mountain Contour, and reported by publisher Gryphline.
Players should monitor their local server status to determine if they fall into the June 4 or June 5 window [2]. The timing of these updates often involves a maintenance period that temporarily takes servers offline before the new version becomes available to the public.
“The update launches on June 4 or 5, depending on your time zone.”
The rollout of version 1.3 demonstrates Mountain Contour's commitment to a consistent live-service cadence. By introducing titled updates like 'Sketches of Lost Heirlooms,' the developer aims to create narrative milestones that encourage lapsed players to return and current players to invest more time in the game's ecosystem.
