As one of the many people who may have started your MOOC but not completed it (and of course as someone who knows you from before that experience) a few thoughts from both my own experience and reactions to your essay.
Complexity in experience makes is more likely to stop the experience (whether a MOOC or an in-person class) or at a minimum detracts from the evaluation of that experience. Specifically the MOOC was a bit unclear (still is) for how to catch up on it if life intervened and you didn’t keep up. Likewise I can imagine that a flipped classroom could make catching up if you miss a few days seem an insurmountable burden.
(side note — in my own college experience I took one unusual course — a three quarter course that started in the winter quarter, then the spring quarter then the fall quarter of the next year — which was odd enough but then the structure of the course was a single class each week for 3 hours, in the evening typically at a classroom in the library. While theoretically an undergraduate course it had many graduate students in it and the reading list for the course contained “optional” works in 3–4 languages other than English and was generally 1 full book a week plus many articles or chapters of other books. I recall at one point literally being some 2000+ pages behind on the readings. In the course of three quarters I recall a Q&A opportunity only once and the tests could and did include content from footnotes in the readings never once mentioned during the class. All that aside — I still remember that course nearly 25 years later so something of that model “worked”)
In the case of your gamification course I wonder if there is a correlation in evaluations between students who “got” all of the puzzles and hidden game elements (and thus felt like they had “won” and the likely far more common case of students who missed getting things on their own — either having to ask fellow classmates for hints/clues/answers or never getting the hidden elements (I think I never figured out your easter egg in the early MOOC videos for example). That combined with likely falling behind if you missed a few classes could help explain the lower than typical evaluations.
And related to that I suspect that low evaluations reflect a disconnect between expectations going into the course and the reality of the course day over day and by the end of the course. If you expect one thing (from the course description and/or past student’s perspectives) but experience another it is not unlikely you will have a sense of something being disappointing even if you can’t express specifically what was “wrong” with the course (or the teacher/content/format etc).
Adding in a “flipped” classroom that most people might not have yet experienced probably increases this effect.
I think as well aspects of the “flipped” classroom work better for some people than others. For example when I’m learning something I strongly prefer to read text (on a page or computer screen or both) over hearing audio or viewing video. I read, when I want to and am focused on it, really really fast — faster than I can I listen to audio or watch video. And I’m more focused on the content than I am on listening or viewing video. And my recall of that content is far far stronger when I have read it than when I have heard or viewed it. But for others watching video or hearing audio is vastly better than reading 100’s of pages of content.
And for many topics I learn even better when I then also try to apply and experiment with the content I’m trying to learn — either on my own in partnership/competition with fellow students. When I was first in college I was also highly distracted by being a teenager living on my own for the first time. When I went back nearly a decade later to finish most of my coursework I was far more focused — and I learned far more from every class I took. I suspect if I had the time to go back to school today I would also learn far more now than I did as a teenager — not least because I was going back on my own terms (and if I were going back I would be valuing my investment in time and money very highly).