Seven piano variations in seven modes. The tonic of each variation descends from the previous one by step, and the key signature of each has one fewer sharps than the previous one.
Here is how I structured the pieces. If I were to identify each mode using only the white notes on a keyboard, I would get C Ionian (major) = 1, D Dorian = 2, E Phrygian = 3, F Lydian = 4, G Mixolydian = 5, A Aeolian (natural minor) = 6, and B Locrian = 7. I have used these numbers to influence the time signature of each mode, so, for example, Mode 6 is in 6/8 time.
Then, starting with B Mixolydian (4 sharps, Mode 5, in 5/4) I then proceed through A Ionian (3 sharps, Mode 1, in mixed time), G Lydian (2 sharps, Mode 4, in 4/4), F# Locrian (1 sharp, Mode 7 in 7/4), E Phrygian (no sharps or flats, Mode 3, in 3/4), D Aeolian (1 flat, Mode 6, in 6/8), and C Dorian (2 flats, Mode 2 in 2/2).