I don't particularly feel that there is an opposition between those two qualities. Particularly, if you consider "mechanics" to their finest grained, they are a complex of human biocultural stuffs and computer software (itself material culture & technology). This is the same stuff that produces spatiality in games. As approaches, though, they might be distinct. A mechanical approach tends to be focused on more board-gamey macro design, whereas an approach focused on experience might focus on the aesthetic qualities of particular components (software and otherwise) of the game. There is also a literary approach, which treats games as a narrative text. I suspect that range of such approaches exist. In the sense that you may invest your time into one approach or the other & must manage conceptual conflicts between serving the needs of each, I guess that you could consider there being an opposition between them. But reconciliations and combined approaches are certainly possible, so by working at it, the seemingly opposed may meld into a third thing. For me, games are programs produced by doing work & cooperating. As software is such an astoundingly general thing, it naturally welcomes many different approaches.
Yes exactly, I don't think there's any opposition between immersive gaming and mechanics, where we might disagree (I don't know) is that I think immersive stuff simply won't exist until they have corresponding gameplay mechanics.
When I see a wall I can jump off of in Super Mario 64 I think that imbues it with a kind of potentiality, and that neither detracts nor sits separate from its aesthetic or immerisve value. In fact I think this is laying the ground work for certain kinds of emotions to occur. Moving a floating camera through a hallway in Mario 64 is I think very different than walking along with Mario down that same hallway. That hallway is made manifest beyond being a 3D shape because of Mario's abilities relative to it. I think this is the same reason why that Grandpa game struck a chord, pieces of the gameworld are willed into existence because of the players abilities relative to those parts of the landscape.
I think that we think roughly along the same lines, but my version is that "the player experience & culture can't exist without game software capable of producing it". The reason I'd phrase it that way is that I think immersive experience for an individual player is only one of many possible goals. The reason I say game software is that "mechanics" seem to have come to refer to one specific school of thought (drawing from board games and conventional wargames and rpgs) used to build the game software (including the text, pictures and other data embedded in it), whereas all vidja games involve a program and a computer and some i/o devices. Game components is also a suitable (and more general) word.
I definitely agree about the different manifestations of game objects relative to the player / player character's relation to it. One of my earliest mature (i.e. after high school) thoughts about game design was that we can understand games as being a flowing system of expanding and contracting potentialities & possibilities in the game space. But it was more of a hypothesis than a result. I had been trying to understand game design better by learning about graphic design and "potentiality" was my immediate answer to the question "for game designers, what is whitespace?" But to find a way to use the idea for anything, it seemed necessary to figure out how software can cause people to perceive & grasp possibility and how we can understand these systems of possibility in a general sense.
Obviously it turned out to be an incredibly complicated topic in a whole heap of different ways but the partial conclusions I have come to are:
1. Game design doesn't exist except as planning for game construction. It's not really a thing in itself.
2. The production of software and the production in and of the surrounding culture are inseparable.
3. The 'potential' is roughly the same as a partial mental map of a space produced by the software.
4. The game space is a dialectic between the state-space of the game software and the player-community's understanding of it. Actually it's probably a bigger dialectic mess than that but I'll have a better idea when I've finished reading Lefebvre's book (The Production of Space) and maybe done some more math. That whole research trail is a big unresolved timesink.
5. That means that's it's not so simple as I initially thought it was (flow of potential / state-space around the player-character). It's not wholly determined by the player's abilities because the player's expectations, their limited information about the data and rules of the game, and the situation of the whole thing in a wider cultural web.
Idk if that's all entirely related to what you're talking about but I think we're in a similar region in terms of what we think. I can elaborate on why I think these things if you are interested in any of them, although how thought-out my opinions are varies.