Based on the code of Fangorn's CliFrotz 1.6, CellarDoor maintains support for Z-Machine story files, while adding support for Glulx stories, as well as Z-Machine and Glulx stories wrapped in the Blorb file format (.zblorb and .gblorb files).

CliFrotz was based on the Frotz v2.43 interpreter. Frotz is an Interactive Fiction interpreter that plays Z-Machine (Infocom, Inform, Z-Code) games such as Zork and Hitchhiker's Guide to the Galaxy. CliFrotz supported V1-V8 games and V6 MG1 graphics.

CellarDoor adds Glulx support via the Git interpreter (1.2) and uses a (rather) modified version of the CheapGlk library (0.9.0).

It supports JPEG and PNG graphics, if they are found in Blorb files. It requires a hi-res screen, OS4 or later, an expansion card and the large dynamic memory area available from OS4 onwards. If your handheld does not meet these requirements, you may want to try Frobnitz, PilotFrotz or Kronos.

Update Description:
v1.0.2:

• Fix for nasty crashing bug with the command history: trying to access or insert a command into the history on a 2nd game launch in the same session (e.g. play a game, close it, play a new game) had an excellent possibility of corrupting memory, causing instability and resets.
• Infocom V6 stories, if the graphics can't be loaded, or (for blorbs), if graphics have been disabled, no longer exhibit screen corruption, and are now playable. "Zork Zero" (non-blorb) is an exception, and hangs CellarDoor (and Frotz). The "Zork Zero" blorb works fine with or without graphics, and in general, you should now be running all of the Infocom V6 games as blorbs, even if you have graphics disabled, so that they scale properly. There's now code for coaxing width and height info out of blorb data without using the graphics plugins, so that the screen will format correctly, even if nothing is drawn.
• Fix for input behavior in some games when tapping on the text entry line, whereby the cursor would jump back to the end of the line when you are trying to place it somewhere else.
• Fixed eternally old cosmetic problem from back in Frobnitz days, where interface text and/or the 'MORE' prompt would get underlined, if the text at the moment where it's made visible is underlined.
• Improved compliance: ZCode color now handled like DOS/WinFrotz - bold is brighter than normal style. This allowed me to remove several color hacks, and Varicella is still playable. CellarDoor now passes item 5 in etude.z5.
• Improved compliance: ZCode 'pre-loading of input line' now works better (there were some positioning issues, and the interpreter was redrawing text already drawn by the game). Item 12 in etude.z5.
• Improved compliance: After a 'clean' end to a game (quit, win, etc.), CellarDoor prompts for a single key press/input event before returning to the Story List. Item 14 in etude.z5.
• That means we're 100% for etude.z5, by the way.
• Improved compliance: Glulx games which do not specify a style or color for status windows (e.g. the header) don't automagically get reverse text. Reverse text looks better in many cases, but causes unwanted behavior when entering text in those windows.
• Selection and scroll position are now remembered when you return to the Story List from the interpreter.
• Graphics on/off and bit depth are now hidden from the user during game play. They may be set from the Story List.
• Improved program behavior if the memory card is removed from play. Your game will get safely autosaved, and CellarDoor should gracefully exit.