Ozmoo Release 14.36

We have just published Release 3 of Ozmoo, the free Z-code/Infocom interpreter for the C64. Compared to Release 2, which came out in June 2019, this release has:

  • Darkmode - a secondary, configurable, colour scheme (Player hits F1 key to toggle).

  • A configurable splash screen just before the game starts.

  • Support for four new languages. Apart from English, Ozmoo now supports Italian, Danish, Spanish, French, German and Swedish.

  • Many bugfixes.

For more details, read the release notes at Releases · johanberntsson/ozmoo · GitHub

There is a full presentation of the project on the homepage at GitHub - johanberntsson/ozmoo: A Z-machine interpreter for the Commodore 64 and similar computers

The easiest way to use Ozmoo to build games for playing on a C64 or emulator is by going to Ozmoo Online: http://microheaven.com/ozmooonline/ . This web page has received many enhancements as well.


Merry christmas, Ozmoo Release 5 is out!

What it is: A Z-code interpreter for C64 (and more, read below!)

What’s new since Release 4: LOTS of changes, but the biggest news:

  • Support for C128 (80 and 40 col, 2MHz when possible, 1571 drive)
  • Support for Plus/4 (+ C16 w/ 64K)
  • Support for Beyond Zork on C64, C128 and Plus/4
  • Progress bars while the game loads data into REU or RAM
  • Better control over preloading (parts of the story which are loaded before the game starts, to get less pauses for disk access during gameplay)

Read what changed: https://github.com/johanberntsson/ozmoo/releases

Try it out: http://microheaven.com/ozmooonline


Steve Flintham has done an amazing job of porting our Z-code interpreter Ozmoo to Acorn computers. Ozmoo for Acorn supports various Acorn computers, a co-processor, sideways RAM, shadow RAM, multiple screen modes… Impressive stuff!

You can find it at Ozmoo for Acorn | zornslemma.github.io


Ozmoo Release 6, Z-code interpreter for C64, C128 and Plus/4 is out!

Highlights of this release:

  • Command history (use cursor keys at prompt)
  • Selectable input text colour
  • New font included: Clairsys Bold, by Paul van der Laan (used in image below)
  • Faster & with less bugs

Read more and download at Releases · johanberntsson/ozmoo · GitHub

Use online at Ozmoo Online


Ozmoo Release 7 is out!

Ozmoo, as you may know, is a Z-code interpreter, originally written for the Commodore 64. In December 2020 we announced support for C128 and Plus/4, and there is also a version for Acorn/BBC.

Big news: You can now build games for the MEGA65! (Porting credits: Paul Gardner-Stephen)

Also: Score/Moves in z3 statusline are now printed separately on 80 column screens (MEGA65 + C128)

Read more and download it at:

[Releases · johanberntsson/ozmoo · GitHub]

Use Ozmoo Online to build games using Ozmoo:

[Ozmoo Online]

Picture: Ozmoo 7 live on a MEGA65 devkit.


We have just released Ozmoo 8, our Z-code interpreter for Commodore 64, 128, Plus/4 and MEGA65.

The biggest news: Optimizations to make Ozmoo crazy fast on MEGA65, meaning you can definitely play large Infocom and Inform 6 games.

Note: Some large games have too much dynamic memory and can’t be played for that reason, and Inform 7 games are still out of the question.

Read release notes and download: Releases · johanberntsson/ozmoo · GitHub

Use online: Ozmoo Online


This looks cool!


Ozmoo Release 9 is out.

News: Support for z1, z2 and z7 story files.

Ozmoo Online has been updated with the new version.

Also, I made a collection of the first (z1) version of Zork 1, the first (z2) version of Zork 2, and Henrik Åsman’s replica of the 285 point version of Zork from June 14, 1977, plus the best z3 releases of Zork 1, 2 and 3, for C64, C128, Plus/4 and MEGA65:



Ozmoo 10 is out. Some news:

  • On the MEGA65: Supports sound effects
  • On the MEGA65: Can play games regardless of dynamic memory size
  • On the MEGA65: Can play lightweight Inform 7 games, thanks to the new ability to use a 16 KB stack (+ a decent CPU speed)
  • The user can specify a disk title when building a game, e.g. make.rb zork1-r88-s840726.z3 -dt:"zork 1"

Get it at Releases · johanberntsson/ozmoo · GitHub

MEGA65 builds of the two Infocom games that include sound can be downloaded at https://files.mega65.org/?id=d02dbdc4-6e1e-4f27-9656-a56b69ca0ca0

A short video clip showcasing the sound option is available at https://twitter.com/FRamsberg/status/1537248040997769218


Ozmoo Release 11 is out.

  • Biggest news is a new Scrollback buffer feature, letting the player scroll up through text that has scrolled off the screen. Requires a MEGA65, a C64 with REU or C128 with REU.

  • Ozmoo used to hope that the REU was big enough to hold the story file. Now it calculates the size and figures out if it can be used to hold the story file, a scrollback buffer or both.

  • Some commandline arguments have changed a bit. Most notable change is that option -dd to disable darkmode has been replaced by -dm:0

  • Commandline history is now enabled by default on MEGA65, as is Scrollback buffer.

(See previous posts for links to Ozmoo, Ozmoo Online etc)


Ozmoo has reached v11.25, and now has support for scrollback buffer in RAM on all platforms. If you enable this on a game for C64 or C128, Ozmoo will still use an REU for the buffer is available.

Ozmoo Online has been updated with the new version: Ozmoo Online


Commodore 64, 128, Plus/4, MEGA65 text adventure interpreter Ozmoo, Release 12 is out!

Includes support for tear-free scrolling (most platforms) and, thanks to Dennis Holmes, smooth scrolling (C64 and C128 in 40 column mode).

Lots of optimizations and bug fixes as well!

See the release details at Releases · johanberntsson/ozmoo · GitHub

Build your own disk images for Infocom games or other Z-code games at Ozmoo Online

Watch some smooth scrolling action at Ozmoo 12 Smooth scrolling - YouTube


Ozmoo 13 is out. As far as we know, this is the first Z-code interpreter for 8-bit machines that supports Undo.

Undo requires a C64 with REU, a C128 or a MEGA65.

[Releases · johanberntsson/ozmoo · GitHub]

[Ozmoo Online]


Ozmoo 14 has been released. Main news:

  • Adds support for the Commander X16 target
  • Save files can be moved between builds, Ozmoo versions and platforms, for MEGA65 and Commander X16.

Release info and downloads at Releases · johanberntsson/ozmoo · GitHub

Build your games online at https://ozmoo.online


Ozmoo 14.7 is out, with important bug fixes and added features for Commander X16:

  • Custom fonts (nice to have for games in English, crucial for games in many other languages)
  • User-selectable scroll speed, and tear-free scrolling
  • Fast restarts (static part of the story file isn’t reloaded)
  • save/restore had potentially game-crashing bugs, depending on ROM version on Commander X16.

Using the custom font option (available on C64, C128, Plus/4, MEGA65 and Commander X16), one can play games in German, French, Italian, Spanish, Swedish and Danish (other languages are possible too, but require some work). Screenshot below shows Äventyr, a Swedish translation of Adventure.


Ozmoo 14.29 is out. Some highlights of what happened since 14.7:

  • User can create a .ozmoorc file to set paths to executables, e.g. X16 = C:\emu\x16emu.exe. .ozmoorc can be located in $OZMOO_HOME, cwd, or $HOME . This should make it a lot easier for users to update Ozmoo.
  • Scrolling was made 3.5x faster on Commander X16
  • Ozmoo can now auto-expand “x” to “examine”, controlled with -x, enabled by default in Infocom games that benefit from it
  • Numerous bug fixes.

In other recent news, Ozmoo Online now supports building disk images for Acorn/BBC computers as well.


Ozmoo Release 14.36 is out!

It supports UNDO on Commander X16 (already supported on C64, C128 and MEGA65), so you can take back your last move when you mess up! Has optimizations and bugfixes.

Picture: Vacation Gone Awry on Commander X16