An interpreter for all Infocom games Frotz is a Z-machine interpreter. The Z-machine was a virtual machine designed by Infocom to run all of their text adventures. It went through multiple revisions during the lifetime of the company, and two further revisions (V7 and V8) were created by Graham Nelson after the company`s demise. The specification is now quite well documented\; this version of frotz supports version 1.0. Frotz is superior to Pinfocom and Xzip.