Busoni's magnum opus is a colossal synthesis of Bachian counterpoint and 20th-century virtuosity. It is distinctive for its vast scale and the intellectual intensity of its fugal development.
At Henle 9 this is among the most demanding works in the piano literature. The main demands: independent voices that must each sing on their own line; big chords that need weight without harshness; and chord voicing — bringing out one note inside a handful of others.
Beyond that, expect several simultaneous layers, each needing its own dynamic level, and polyrhythms that have to lock together without sounding mechanical.
At roughly 25 minutes, stamina and memory become part of the challenge — plan practice in sections.
The performer faces extreme challenges in managing the massive vertical textures and sustained intellectual focus.
Comparable difficulty and character — good candidates for what to learn next.
A level or two down with the same spirit — ideal if this piece is still out of reach.
Lesser-known works by the same hand, at a comparable level.
Fantasia contrappuntistica is rated Henle level 9 of 9 — virtuoso repertoire, roughly concert / virtuoso level. In the RCM system it corresponds to about level 10.
You should be comfortable at Henle level 9 — meaning you can already play level 8–9 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 Fantasia contrappuntistica lasts about 25 minutes.
Fantasia contrappuntistica 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 Fantasia Contrappuntistica, BV 256 by Ferruccio Busoni, Fantasia Contrappuntistica, KiV 256 by Ferruccio Busoni, Canonic Variations & Fugue in C Minor by Ferruccio Busoni — see the full similar-pieces list on this page.