ประตูของพ่อค้าและนักเล่นแร่แปรธาตุ

Missing, extremely new, or very obvious to obtain.

A reference to the 2007 science fiction short story of the same name by Ted Chiang. The story is about a fabric merchant who hears about three people who traveled through a gate made by an alchemist to meet future selves and their fates, and the merchant also learns about a gate made by the same alchemist to meet past selves and people they've met in the past. Rerolls and cheats (which you need to use a lot of for this achievement) can be interpreted as ways of either changing what you have done in the past or changing what you will do in the future.