Well, being an Operating System, there have been many things programmed "in Emacs": * email, slack and reddit clients * web wowser * tetris * Amazon's customer

Well, being an Operating System, there have been many things programmed "in Emacs": * email, slack and reddit clients * web wowser * tetris * Amazon's customer service handling https://tess.oconnor.cx/2006/03/quality-without-a-name https://tess.oconnor.cx/2006/03/quality-without-a-name (not sure what that says about Emacs Lisp. Or Amazon.) * PIM / OCD management software * video editing https://www.nongnu.org/gneve/ https://www.nongnu.org/gneve/ * mind control https://github.com/jonnay/mindwave-emacs https://github.com/jonnay/mindwave-emacs * Thermonuclear word processor * vim and vi emulators, if you ever need to use it for coding * Internet of Toys https://news.ycombinator.com/item?id=29207607 https://news.ycombinator.com/item?id=29207607 * Air traffic control system https://news.ycombinator.com/item?id=33524683 https://news.ycombinator.com/item?id=33524683