My better half and I sometimes play the Roman Numeral Game when recorded music is playing—film credits, grocery shopping, and so on. In this simple diversion, we hold up a number of fingers indicating the appropriate Roman numerals corresponding to the harmony that’s happening at the moment in the music. Importantly, the Roman Numeral Game is played in time; the greatest achievement is to play it on top of the beat to music we’ve never heard before, relying on our knowledge of convention to predict the upcoming chord progressions.
Although I’ve never deployed the Roman Numeral Game in a pedagogical context, I suspect it might be a useful exercise, especially in the realms of homophonic popular musics and large-C Classical music. On the other hand, considering how much mental computation goes into the RNG—determine key, determine bass, determine root, assess chromatic adjustments—a considerable facility with Western music is required to play. Last week I had occasion to explain to a nonspecialist what exactly the difference is between A7, D7, G, C and Am, Dm, G, C; in order to understand dominant emulation, though, one first has to understand what a dominant is, and in order to understand that one has to understand how harmonic functions are related to scale degrees, and in order to understand all of this one has to know how triads are constructed.
You can only explain Western music as a history of productive deviations from slowly changing normative practices if you first explain those normative practices, and you can only explain normative practices if the person you’re talking to knows that C-sharp and D-flat are not the same note. (On the plus side, this episode made me feel much better about getting paid to teach music theory.) However, I’m sure everyone reading this post could hack the RNG with no trouble. Ideally it’s played semi-competitively, but the goal is less to lord one’s victory over a disgraced foe than to give air to interpretive disagreements: What’s the Roman numeral of this augmented 6th chord? (Hint: probably II.) How about this tritone sub?
So take it from me: Hours of entertainment and spirited discussion await you! The Roman Numeral Game is the world’s premier free hand-based common-practice surface-level harmonic analysis amusement technique.