Ah, a technical discussion! :) Sure, I'd be happy to dig in further into the details.
> Why do you think using genres to measure knowledge diversity is questionable? What is your concern about doing so? Please elaborate if you seem to have such a strong opinion on that.
Sure. Basically I treat a genre as a family of design solutions to a particular set of constraints, reified as artifacts. A genre will carry with it answers to a lot of question around who the player is, what is their role in the world, what kind of actions they can take on what kinds of objects (i.e. mechanics) and so on. In a sense, the choice of a genre answers a lot of the broad questions, letting the author delve deep into more detailed questions.
Going back to the author metaphor - it's like saying, Eco is lacking knowledge diversity because he mainly wrote books that tackled issues around meaning and semiotics. Sure, he never wrote any comic books or young adult novels. But that by itself is not a problem - that doesn't mean he had low "knowledge diversity" - especially since when he wrote about meaning, he dug deep into everything that related to it.
So in my design practice, I don't see deep expertise in specific genres as equivalent to "low knowledge diversity". Very much the opposite.
> Using the mashup of mechanics to measure novelty seems logical for two reasons. First, in creativity research, it is quite common to measure novelty as uniqueness or as distinctiveness regarding already existing "solutions."
What gets me here is uniqueness/distinctiveness purely based on taking mechanics and converting them into a distance metric. There's much, much more to a game than that! A game can be unique even when it shares a lot of mechanics with its predecessors. Indeed the whole history of game development is an evolution of designs, which are in conversation with what came before them - as in all arts, really.
Again, imagine complaining that Georgia O'Keefe had low "novelty" because she used traditional painting materials and composition.
> Second, the authors refer to the MDA framework in their method section as an explanation of why they use mechanics. Following this framework, mechanics are not only the core elements of a game but also the only thing a game designer is able to influence - not the dynamics (i.e., run-time behavior, which seems to be "gameplay" in your wording) nor aesthetics (i.e., emotional responses of the player, which seems to be "non-game play" in your wording).
So, a few things. Per MDA, mechanics are the only material elements of gameplay design that designers can influence - gameplay, as in the behavior of the game once it's put into motion by players. But they're not the only material elements of the game itself! Beyond just the aesthetics of interacting with game rules (the A in MDA) there are also sensory aesthetics, audiovisual aesthetics, and other elements of appreciating the game artifact on a material level.
But on a deeper level, just because M in MDA is the material substrate that designers can influence, that doesn't mean that's the interesting level to focus on. For example, take a game like Universal Paperclips. If we focused purely on the mechanics, it's a fairly tedious game with bog-standard resource loops. But if we look at the larger loops that the player participates in, and boosted by the innovative fiction (innovative by clicker game standards at least), the overall player experience is very different from what you'd expect by just looking at the mechanics!
And we could do the same exercise for basically any game. Just looking at the mechanics is reductionist, in terms of what the game brings to the table (as it were ;) ).
So that's the main problem I have with looking at just mechanics, and proclaiming a distance vector in mechanics as an novelty metric. It completely misses the forest for the trees.
Hope this was useful! Or at least enjoyable :)