> The 45 degree rotation does require more dual input than I care for which makes me wonder if that is a design choice.

Well they say "A Marble Madness-inspired WebGL game" so there is not much choice about the rotation [1]

[1] https://en.wikipedia.org/wiki/Marble_Madness

The NES Marble Madness port (and probably others) had a choice of control schemes, where the D-Pad is either mapped directly to the screen (Down is down) or mapped at a 45 degree angle (Down is down-right). I never could wrap my head around the latter, but I can see the benefit given the stage layout mostly uses 45 degree paths.

Looking through the linked docs I see the physics frameworks.

Of all the programming I find the 3D gaming to be the most complex and unattainable at my current knowledge or intelligence level.