I'm not a lawyer or particularly strong with English, but at least it makes sense in this interpretation.
Except it's used under license from naturalmotion, and naturalmotion owns the code (hence the copyright naturalmotion).
Yet, naturalmotion explicitly grants no rights.
I can state affirmatively this makes no sense :)
As I said, either they've granted rights (through justin), in which case that statement that they grant no rights should not be there (because they are in fact, granting rights) Or they haven't granted rights (through justin), in which case it's not open source and who knows what rights you are getting here.
What the copyright stuff means to me is that I'm not allowed to relicense, but i could modify or distribute unmodified.
However, the language defining step (b) ("granted by Justin Webb with the permission of NaturalMotion Limited") is hand-wavy and doesn't spell out exactly what rights are granted, so I would agree that this seems legally pretty shaky. What rights is NaturalMotion intending to reserve by including the following sentence? If there are any, do they conflict with the ability to redistribute under a BSD license? If there are none, why is that sentence there ar all?
There is a difference between Open Source and Free Software, but it's ideological, not technical (as pertaining to the rights granted to the users of the software).
This is what shared source is about. Open source is nearly always used as defined by the OSI:
For an official example of the use of the term "open source" to mean "you can read the source but are not allowed to do anything else with it" see the 2007 announcements about QNX. OSI explicitly declared there is no (OSI) open sourcing in what QNX did at the time. https://opensource.org/node/195
For an example of people using the term to mean only "you can read the source" look no further than the discussions related to the recent leaking of Amiga 3.1 source code where people were debating if an effort can be made to convince the copyright owners to "open source" the code: "Correct me if i'm wrong, but open source doesn't have to equal FOSS. I'd be inclined to agree with you if it were FOSS, but just being open source could provide 'assistance' to Cloanto who can incorporate peoples ideas/fixes but still retain the right to sell it when others don't. Managed well, could it actually be beneficial to Cloanto and the broader Amiga community?" "You are correct. FOSS and Open Source are not the same. Permissive licensing doesn't have to be attached to the opened source." "This is true, but nobody suggested it should be FOSS, me included. Open sourcing of any kind just isn't going to happen without some sort of miracle."
Unfortunately the term "free software" is a terribly ambiguous one (and Richard Stallman and the FSF are to blame here since they knew about the homonimity of the word "free" beforehand) And even more unfortunately "open source" has for a long time become ambiguous. You can not rely on "open source" meaning "OSI open source" to everyone you talk to. And members of both organisations and their supporters spend a lot of time fighting about the meaning of each others terms. So we are stuck with the horrible term "FLOSS", an abbreviation of "Free & Libre & Open Source Software" to roughly define what we actually want to talk about: both copyleft ( https://www.gnu.org/copyleft/ ) and copyfree/permissive ( http://copyfree.org/standard ) licensed software (and in some cases also public domain).
You can complain about ambiguous words and RMS having chosen "free" all you want, but these are the terms we have, and we shouldn't give them up too easily.