This is a piano solo version of Armstrong's S-mode variations. The writing focuses on atmospheric textures achieved through modern intervallic relationships.
Students must develop a nuanced touch to distinguish the modal colors within the variations.
Comparable difficulty and character — good candidates for what to learn next.
12 Variations in S-Mode, for piano solo is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 6.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of 12 Variations in S-Mode, for piano solo lasts about 5 minutes.
12 Variations in S-Mode, for piano solo is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include 12 Variations in S-Mode by Peter McKenzie Armstrong, 12 Variations in S-Mode by Peter McKenzie Armstrong, Black & White, for piano solo by Peter McKenzie Armstrong — see the full similar-pieces list on this page.