[aspirin]

I believe he means that in digital games the model stays hidden most of the time. You only see the inputs and outputs.

In physical games the players have to enact the model themselves by following the rules at every step. Without exact knowledge of the model, the gameplay cannot even start.

[TillE]

Yes. With computer games, the actual rules are almost never completely described somewhere. They must be divined by trial and error.

A good example is Hearthstone vs. Magic: The Gathering. Hearthstone has all sorts of non-intuitive edge cases and unwritten rules. M:TG needs to be fully understood by all players, so complex interactions are still resolved with a fairly simple set of rules.