YAZI (Yet Another Z-Interpreter) by George Madrid and Sanjay Vakil is a V1-V3 Z-code interpreter for the Apple Newton. It is based an Mark Howell's ZIP and Graham Nelson's `The Specification of the Z-Machine, Standard 0.2'.
The shareware version present here ($25) is somewhat crippled: you can save your game at any time, but the games saved after more than 50 moves cannot be restored in the shareware version.
detailed description of YAZI
Newton Register 1.0.1; can be used to register YAZI
Macintosh package with YAZI Beta
DOS package with YAZI Beta