<b_jonas> slashlearn euclid//Euclid is a short geeky game in which the goal is to do Euclidean compass and straightedge constructions in as few steps as possible. It runs in the browser, found at "http://www.euclidthegame.com/". It was popular among #esoteric regulars in 2016-07.

Obvious, adj.: A postulate used to prove a wide variety of theorems too arduous to prove by other means. In American Sign Language, it is denoted by a vigorous waving of the hands.