PYZ is a Z-Machine interpreter for playing interaction fiction files. Text adventure games written by Infocom, such as the Zork series, used a then-revolutionary virtual machine called the Z-Machine, which saved code space on the memory-limited computers of the 1980's. People today are still writing text games, now called interactive fiction, for the Z-Machine platform. PYZ includes a mode in which you can see the instructions being executed, turned on by the --trace option. A test suite, pyztest, tests all the instructions.