World Of Warcraft

A popular online game made by Blizzard with a worldwide following of millions. WoW has two world-usable DomainSpecificLanguages, LuaLanguage for advanced UI add-ons and a macro language (the slash language) for running game commands. (There is also an XML format for specifying user interfaces, but those can be created equally by lua code.)

The UI provided by Blizzard is itself written in LuaLanguage, and stored in the same place as add-ons.

WoW designed the APIs to prevent heavy automation. The slash language does not have iteration, but it has simple conditionals and can run major in-battle commands like spell casting. This allows the user to automate some tasks, like optionally renewing some enhancement on a single player if it is expired. The LuaLanguage extensions to the UI can only create buttons that can be used for those commands.

There is a fairly wide market of UI Mods of various uses. Some replace the Blizzard interface entirely. There is even an Arkanoids clone available, though there are not (to my knowledge) any other arcade-type games.

http://www.wowwiki.com is an extensive community wiki for WorldOfWarcraft using the Wikimedia engine. Unfortunately, there is no facility for formulas, which are present en masse on all pages in the Formulas category...

See DomainSpecificLanguage, LuaLanguage, LittleLanguage