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Chords, a trip away from home

Most songs leave a place and come back to it. A chord progression is that trip: one chord is home, the others pull away from it or toward it, and the loop closes when home returns. Pick one, press play, or type your own.

How to read it

home The chord the key is named for. It sits at the left end of the axis and is always green.
shadow A relative of home (vi or iii in a major key): it shares two of its notes, so it feels like home from the side.
away A chord that leaves home (ii, IV): amber.
pull A chord that wants to go home (V, vii°): red-orange.
colour A chord from outside the key, borrowed or briefly pointing at another chord: violet and dashed.

Height is tension: how restless the chord is, from its job in the key, its dissonant intervals and how far its root is round the circle of fifths from home.
Minor chords are cooler and less saturated than major ones, and the shapes differ (an open triangle for major, a folded one for minor, a spiked one for a dominant 7th, a jagged star for diminished, a bar for suspended), so nothing depends on colour alone.
Tempo changes how often the chords change. It never changes how far or how fast anything moves.

The six progressions

The four-chord loop I–V–vi–IV
The 50s progression I–vi–IV–V
Twelve-bar blues I–IV–V in 12 bars
The Andalusian cadence i–♭VII–♭VI–V
Pachelbel's Canon I–V–vi–iii–IV–I–IV–V
ii–V–I ii7–V7–Imaj7

Sources

Wikipedia: I–V–vi–IV progression · The axis progression; rotations such as vi–IV–I–V; the table of songs that repeat it at least four times in a row
Wikipedia: '50s progression · The '50s progression, I–vi–IV–V, also called the doo-wop progression; the list of songs containing it
Wikipedia: Twelve-bar blues · The basic twelve-bar form on I, IV and V, dominant sevenths, and the AA′B melody
Wikipedia: Hound Dog (song) · "Hound Dog" is a twelve-bar blues song by Leiber and Stoller; Big Mama Thornton recorded it in 1952 and it was released in February 1953
Wikipedia: Red House (song) · "Red House", written by Jimi Hendrix, has the musical form of a conventional twelve-bar blues; first released on the British edition of Are You Experienced in May 1967
Wikipedia: Tutti Frutti (song) · "Tutti Frutti", Little Richard, released October 1955, with a twelve-bar blues chord progression
Wikipedia: Andalusian cadence · The i–VII–VI–V descent from flamenco, most often an ostinato; rock songs that use it
Wikipedia: Pachelbel's Canon · The canon's eight-chord ground bass in D major, its 1968 revival, and pop songs that use its chord progression
Wikipedia: ii–V–I progression · Roots descending in fifths from the second degree to the tonic; its use in jazz; songs that include it