Suppose you were able to open a portal to a dimension in which physics behaved perfectly classically. Every interaction in this "world of forms" is accurately described by classical and Newtonian mechanics.
What would this world look like? What quirks would there be to it? What could you exploit?
Obviously, without relativity, it would be possible to accelerate to infinitely high speeds.
Additionally, I'm inclined to believe that no big bang-like event could occur, meaning this dimension would just be a vast store of equilibrium temperature hydrogen(?). I think magnetism would still function, but Maxwell's equation and its associated theories wouldn't, so you would have no induction.
However, I'm sure there are anons out there with more Physics education (and imagination) than I, who could better conceive of the implications of, say, the photoelectric effect no longer occurring.