guitar scale
F♯ whole tone
Six notes, every step a whole one. There are only two of these scales in all, and every note can be heard as the tonic.
The same sounds spelled from the other side are G♭ whole tone.
Written out
Every accidental is written in, rather than left to a key signature, so the letters can be read one at a time.
The step pattern
What is true of it
F♯ whole tone is F♯, G♯, A♯, B♯, C𝄪 and D𝄪, and back to F♯.
Its steps are W – W – W – W – W – W, where W is a whole step and H a half.
Written correctly it needs 8 alterations, C𝄪 and D𝄪 among them. That is what the letters force, and it is also why nobody writes music in this key: the same notes spelled from the other side are easier to read.
Across the first twelve frets of the guitar its notes fall in 39 places, which is what makes a scale a shape rather than a list.
Chords made only of these notes
Found by testing every chord in the catalogue against these 6 sounds, not chosen.