Thanks for the replies, folks! Really interesting! :)
... Scrum doesn't fail here. It's just the nature of the problem and there's no solution to it other than changing the problem to be one of greater predictability or letting scope be flexible if you're going to fix the ship date. ...
The reason I call that a failing of Scrum is that I actually visited some Scrum courses where the trainers said that Scrum would make you meet deadlines. If Scrum doesn't really claim to do that, then of course Scrum does not 'fail' in that regard.
However, meeting deadlines is one of the most important goals of project management. Either by working more efficiently or by doing better estimation so you can set less unrealistic deadlines. I am not aware of any methodologies that 'solve' this problem reall well though. I am just concluding that Scrum does many things well, but does not provide a really good solution to one of the most important issues.
I would like to also take issue with your understanding of "potentially shippable". The purpose of this is simply to convey that what you've completed to this point is "done" according to your definition of done and to drive down risk and drive up value as early as possible.
The only reason I took such a literal interpretation of "potentially shippable" is those Scrum trainers who claimed that Scrum would make you meet deadlines because whatever you had at the last Sprint was releasable. If "potentially shippable" is interpreted in a more lenient way, then their point falls apart. I totally agree with you that it shouldn't be used to literally. :)
I also take issue with your claim at the end of the post that Scrum is bloated with too many rules. There are actually very few rules in Scrum and it's very simple.
Scrum is lightweight compared to most other methodologies, but still most trainers cannot fit all of the core principles into a presentation of one hour. Just look at the Scrum Wikipedia and you'll see that there are a lot of different meetings and artefacts that you need to know about to do Scrum well.
So can you share with us how you use other project management methodology to meet deadlines?
I am not claiming to have a better solution, only that Scrum does not solve the very important problem of meeting deadlines, while some Scrum trainers say it does.
No, it isn't the certification requirements that need to be "implemented first". Those requirements are a quality invariant that should be captured in the Definition of Done.
Unlike what I suppose you seem to think, certification requirements are not something that you just need to keep in mind with everything you build. There are a lot of requirements there that every game developer just needs to implement separately and the whole set of requirements can easily take months to build, especially for developers who are new to console certification.
Some requirements are part of a system (like error handling), so you might argue that those should simply be implemented with the system. However, those are often so much work to get completely right that in game development it is generally much smarter to implement them at a later point. For example, in practice it is best to juist build basic file reading and handle the gigantic set of error handling rules later, so you can first focus on whatever is needed for the game itself.