Guild Wars 2

My Story chapter 8. Victory or Death, section Armor Guard, task Defend the tank column. You step into the marked green circle’s edge and you get a cutscene of the leading NPC saying “Last chance to check your tanks—make it quick. We’re not staying long.” (more or less). Then you run a bit further and touch the other side of the marked circle and the same cutscene plays again.

Also in Armor Guard, moving around the map doesn’t reveal any unexplored parts of the map.