The way I look at it, the only really valuable thing for these old platforms is the game software and IPs. So I just give the tools away since there's no good reason to profit from them or inconvenience anyone else with licensing.
I totally agree ... which is why I want to give away the work that I'm doing on improving the toolset, and put it on github for anyone that wants it.
But in order for someone (guess who) to
legally incorporate your player in a game, or to modify your code so that it assembles with CA65, or to convert it over to the PC-FX, or to distribute your tools on github ... you need to put your intent in a
legal form.
Since you automatically own the copyright on everything that you've written, licensing is a real
legal issue even if there's no money, or attribution, or even any future discussion with you.
You're working at Google now ... if you haven't had the talk on that yet, then I'm sure that it's going to get raised at some point.
The closest thing that I've seen to a
legal version of "giving it all away" is the Boost License. The Zlib license is a very close 2nd, but a bit wordier. I personally prefer the Boost License ... less legal rubbish at the top off the source file.
That's basically a "Do whatever you like with it, and I don't need a credit in your documentation." kind of license.
It's also a legal disclaimer which stops people from suing you if their dog hears a particularly awful chiptune and runs under a bus. Trust me on this ... you
need that legal disclaimer in this day and age.
It would be as simple as adding the following simple notice to
every file ...
Copyright Osman Celimli 2014-2015.
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
It would be nice to also add a link back to your website. Even if your site goes away in the future, there will probably be a copy in the "Way Back Machine" archives.
You really should be the one to do this (especially since you've got the only copy of the PDF source) ... and then release it on your website.
That's how this sort of thing is legally done these days. (Darned lawyers!)
If you can't be bothered to do that yourself ... then I can add those lines to the source files on your behalf ... if you post here that that is your wish, and that those are the correct dates and the license that you wish to use. (But you
really should be the one to do it ... it's one of the responsibilities of an author).
For a comparison of your licensing options, you can look at sites like ...
http://choosealicense.com/licenses/ or
http://en.wikipedia.org/wiki/Comparison_of_free_and_open-source_software_licenses(EDIT)
BTW ... a similar discussion also applies to your layout files for the CD Stupid Card if you want the community here to be able to run off a production batch of cards at some point.