Git repository: Link
Software licenses bother me. As a general rule I prefer to make my projects open source, and for that purpose something like the Unlicense is often sufficient. But if I don't want to put my work in the public domain immediately, then I have to make use of a copyleft license. And all of the ones currently available are both incredibly, unnecessarily verbose, and fail to address the primary failing of modern copyright law, which is the unreasonably long term lengths.
So after a considerable amount of thought, I've written my own. (I can hear those with legal knowledge wailing and gnashing their teeth already.) Care has been taken to mimic the phrasing used in popular existing licenses where possible. I've also kept it as simple and as straightforward as I can make it. So hopefully there are no loopholes and it's exactly as it appears: a simple weak copyleft license which places older parts of a work under a public domain disclaimer in a reasonable timeframe.
The full text is as follows:
SUNSET LICENSE Version 1.0, June 2017 1. You may copy, modify, use, sell, or distribute this work, verbatim or modified, for any purpose. 2. If you sell or distribute this work, whether verbatim or modified, you must include a copy of this license, and you must make the source code available for no extra charge. 3. A modified version of this work must be clearly labeled as such. 4. Derivative works must also be licensed under this license or a license of equivalent terms. As an exception, linking this work with another, whether statically or dynamically, does not impose any license requirements on the other work. 5. If a minimum of 15 years have passed since the date of first publishing for a part of this work, then that part is placed into the public domain and you may do whatever you want with it, regardless of all other clauses.
The git repository also contains an accompanying rationale and a simple logo I threw together. In the future, all my projects will either use this license or the Unlicense. Works I've already created will be relicensed as appropriate.