XCOM 2: War of the Chosen: Each of the Chosen's bases can only be raided once, so you only have one chance to take each of the Chosen out permanently. If you fail to defeat the Chosen in their base, you will not get another chance, and that Chosen will continue to haunt you for the remainder of the campaign.
I removed this because it's closer to One-Time Dungeon, but then I noticed that said trope requires the game to allow backtracking. In any case, it's not a description of the uniqueness rule, but rather only having one attempt at a task.
I removed this because it's closer to One-Time Dungeon, but then I noticed that said trope requires the game to allow backtracking. In any case, it's not a description of the uniqueness rule, but rather only having one attempt at a task.