A contemporary work that explores dense, rapid textures and modern virtuosic demands. It is distinctive for its aggressive use of the piano's range and its percussive, mechanical aesthetic.
The main challenge is maintaining consistent speed and precision across wide-spanning, percussive intervals.
Comparable difficulty and character — good candidates for what to learn next.
20x20 is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 7.
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 20x20 lasts about 4 minutes.
20x20 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 Bien des Compliments à Anne by Werner J.E. De Bleser, All Is Quiet by Werner J.E. De Bleser, All Is Beautiful by Werner J.E. De Bleser — see the full similar-pieces list on this page.