<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.

Esoterra is the planet of Esoterrans, also known as Esolangers. The proof of its existence is non-constructive, although some suspect that it is in fact Earth.