if you wanted to call practomime "playing pretend" or "playing a role-playing game" I wouldn't argue. Think about it: how much do people learn playing pretend, whether that's playing a game, acting in a play, going through a religious ritual, or reading a historical novel? I would contend that it's more than they ever learn in school.
How it works
From a purely technical perspective, the entire course is a big practomime. (In fact, if you think about it, every course you've ever taken [with the exception, to be sure, of my previous courses] is a boring practomime in which you pretend to be a student who's getting to know the stuff he or she needs to know to pass the course.) You are learning to be something like a Roman who could function in some small range of ancient Roman culture.
From a practical perspective, your sessions of reading Latin poetry, however, which would be interludes in the life of the Roman you portray, will in the world of this course dominate his or her practomimetic life. The rest of his or her existence—the times in which he or she gets to "do stuff"—will be squeezed in between the reading. This fact of course means that we get to skip the boring parts of Roman existence (sleeping, walking, eating non-banquet food) and concentrate on the interesting ones.
Roger's doing the kinds of things I dropped cautious hints about in my dissertation, "Acquiring Literacy: Techne, Videogames and Composition Pedagogy." He isn't just making more explicit the connections between college-level coursework and, for example, James Paul Gee's 36 learning principles found in good videogames. Roger made the course the game.
I need to go all in as he has.