There's a certain moment in Stalker 2: Heart of Chornobyl's story, that if activated, will mark as a point of no return for the player. What this essentially means is that players will be locked out of exploring the zone, finishing up any pending side-quests, or simply collecting any artifacts that were missing in their collection. After crossing said point, you'll be put on a linear path that leads toward one of the endings of the game.