Rhythm & Audio

Monkey Island 2 contributes Adaptive Dynamic Music in 1991, with a score that transitions on the beat to follow player action rather than looping until the scene ends. It has no parent in this data, and it is the only entry in the family where the music is the responsive party. Everything else here inverts the relationship and asks the player to react instead.

PaRappa the Rapper does that in 1996 by judging input against a musical grid, which makes time itself the difficulty axis — a direct descendant, per the graph, of Pong's Numeric Score, since what is being scored is accuracy against a standard. GuitarFreaks adds the Scrolling Note Highway two years later, rendering future input as approaching geometry, and it may be the single most efficient interface the medium has produced: a sight-reading system anyone can learn in ten seconds without instruction. Guitar Hero then attaches a dedicated physical object to that highway, and the Instrument Peripheral makes hardware the entire pitch, which is both why the genre briefly dominated retail and why it collapsed under its own plastic.

Crypt of the NecroDancer proposes the family's most interesting recent argument. Rhythm-Locked Action requires every action — movement, attack, retreat — to land on the beat, fusing a music game with a procedurally generated dungeon crawl so that two genres solve each other's pacing problems. Unresolved across all five: whether music should follow the player or lead them. Monkey Island 2 answers one way, the other four answer the opposite way, and thirty years on, no third position has found much of an audience.