Emacs

Emacs is an extensible text editor "family", the most well-known instance being GNU Emacs, released by the GNU foundation and originally developed by Richard Stallman.

Most currently developed emacs implementations share its characteristic extensibility, acting more as a software platform for Elisp (Emacs Lisp) modules. Aside from being a text editor, it can be used to connect to IRC, check mail, run autohotkey-esque scripts, and play simple games.