Free Software IF

Free Software IF is interactive fiction that is released under a license that gives the user:

• the freedom to run the program for any purpose;
• the freedom to study and modify the program;
• the freedom to copy the program;
• the freedom to improve the program, and release your improvements to the public.

Since modifying a program requires access to its source code, free software is automatically also open source software. The reverse is not automatically true: if an author were to release the source code to his game under a Creative Commons Attribution-Non-Commercial-No Derivative Works 3.0 license, for instance, the game would be open source but not free (since distribution of derivative works is not permitted). As another example, the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported license is also not a free software license, since it does not allow people to use the code in certain works, namely commercial ones.

Interactive Fiction released under a Free Software License

GNU General Public License

The most used free software license if the GPL, which is maintained by the Free Software Foundation. The GPL is a copyleft license, which means that all derative works have to be licensed under the GPL as well. This ensures that all derative works are also free software.

GPL version 2

The GPL version 2 was released in 1991. Interactive Fiction released under this license includes:

• The Baron by Victor Gijsbers, Inform 6 (competition release; with 'or any later version' designation).
• GlkChess by Simon Baldwin, Inform 6 (with 'or any later version' designation; not IF).
• The Magic Toyshop by Gareth Rees, Inform 6 (with 'or any later version' designation).
• Silicon Castles by David Given, Inform 6 (not IF).

GPL version 3

The GPL version 3 was released in 2007 to address the issues of software patents, hardware restrictions on software modification ("tivoization"), compatibility with other free software licenses, and internationalization. Interactive Fiction released under this license includes:

• Fate by Victor Gijsbers, Inform 7 (the competition release reads 'version 2 or any later version').
• Figaro by Victor Gijsbers, Inform 7.

MIT License

The MIT License is a very short, straightforwardcopyleft free software license. It is GPL-compatible, which means that projects released under the MIT-license can be combined with projects released under the GPL-license. (Since both licenses are copyleft, the resulting work would have to be distributed under the conjunction of the MIT license and the GPL.)

• baZic by David Given, Inform 6 (not IF).

Home-brew Licences

These programs are released under licenses that the author's have written themselves. As such, details may vary and a careful reading of the license text is necessary.

• The Night of the Vampire Bunnies by Jason Dyer, ported by Patrick Kellum to Inform 6. (Patrick Kellum's code can be used freely, and the license information at least implies that the same holds for Jason Dyer's text and layout.)
• Ditch Day Drifter by Michael J. Roberts, ported by Chris Markwyn to Inform 5.5. ("If anyone wants to finish it off, feel free." Not sure if the original is released under a free license, though.)

Public Domain

Some works are designated 'public domain'. On a plausible interpretation, this means that the author has relinquished all copyright over the work, automatically making the work free software if the source code has been made available.

• All Things Devours by Toby Ord, Inform 6.
• Free Fall by Andrew Plotkin, Inform 6 (not IF).
• The Mad Bomber by Neil James Brown, Inform 6 (not IF).
• Pick Up the Phone Booth and Dye by Eric Schmidt, Inform 6.