Versificator
Versificator is Robin Douglas Johnson's JavaScript text adventure engine.
His games Hamlet, Aunts and Butlers, Portcullis and The Xylophoniad were written in the first version of Versificator, a standard parser interface built to run smoothly in browsers.
Versificator 2 was a complete rewrite of the system as a parser/choice hybrid engine for parser-like games with a contextually generated button interface. This was used for Draculaland, Detectiveland, and Zeppelin Adventure, and The Party Line (later translated to Gruescript.)
Revisions to the world model and verb system were then re-incorporated into the parser version as Versificator 3, used for Gruesome in Parsercomp 2021.
The front-end of Versificator 2 was later adapted to be used by games created by Robin's publicly released scripting language Gruescript.