Although it has taken 14 years, the mighty challenge for one player to record the complete organ works of Sigfrid Karg-Elert (1877-1933) is now complete. Starting in 2003, Stefan Engels initiated his project for Priory with some of Karg-Elert’s most adventurous music, including a magnificent account of the late Triptych, Op 141 (1930). The subsequent 14 volumes have maintained the highest level of musicianship, each generously filled disc featuring a different organ, each of which is either historically appropriate or endowed with the extreme tonal resources that Karg-Elert’s extraordinary scores demand. Criss-crossing the northern hemisphere, Engels played instruments as far afield as Altoona in Pennsylvania, Toledo in Ohio, Trondheim, Ulm, Hamburg, Zurich and, in the UK, the marvellous 1869 Edmund Schulze organ in St Bartholomew’s, Armley, Leeds.

Even now, some 85 years after his premature death, Karg-Elert is probably best known for just one organ work, the ‘Marche triomphale’ (Chorale Improvisation No 59) on Nun danket alle Gott, which most organists will have encountered among the familiar pale blue ‘Collection Simon’ volumes selected by Laurence Swinyard. However, this piece displays but one facet of a cosmopolitan composer whose mercurial personality produced music that could swing in a moment from the epic to the eerie, the magisterial to the quixotic and the plaintively innocent to the bizarrely grotesque.

The youngest of 12 children, Siegfried Karg (as he was born) came to revere JS Bach, was encouraged by Grieg and in thrall to Debussy, and became a natural heir to Wagner, Strauss and the late Romantics. In 1916 he succeeded Reger as professor of composition at the Leipzig Conservatory. His great fecundity resulted in 158 works with opus numbers and 90 without, including important additions to the sonata repertories for flute, clarinet and saxophone, helped, no doubt, by his experience as a German Army bandsman during the First World War. He was also a prolific song-writer, leaving over 125 settings, and spent many years working on an important harmonic treatise, the Precepts on the Polarity of Sound and Tonality.

Karg-Elert’s own preferred keyboard instrument was the Kunstharmonium (he was an indifferent organist) and several of the organ cycles recorded here are arrangements of earlier harmonium pieces. I particularly enjoyed Engels’s imaginative quasi-harmonium registrations, with liberal use of the Vox Humana stop and shimmering ‘stair-rod’ string ranks. In The Legend of the Mountain (Vol 14, on the Link/Gaiuda organ in Ulm’s Pauluskirche), he draws the most extraordinarily vivid colours, using tremulants and a rare Cymbalum stop. At the other extreme, the hefty registrations drawn on the Furtwängler & Hammer Organ of Verden Cathedral in Saxony (Vol 5) overwhelm the wind supply in the Prologus tragicus, Op 86 No 1.

Other highlights of the series include the compellingly radiant ending of the Music for Organ, Op 145, and I have never heard the Passacaglia and Fugue on BACH, Op 150, sparkle with such intensity (both on Vol 13). Nor would I be without the final piece of the 66 Chorale Improvisations, Op 65, an exhilarating treatment of ‘Wunderbarer König’ complete with brass and timpani (Vol 11).

The final volume ties up some loose ends, with transcriptions of music by JS Bach, Halfdan Kjerulf, Mendelssohn and Schumann and – bringing the project full circle – the late, effervescent Kaleidoscope, Op 144. There are important omissions, specifically the Symphonic Canzona No 3 and the Symphonic Chorale No 3 on Nun ruhen alle Wälder (with their violin and soprano parts). The later volumes’ booklets also suffer occasionally from idiosyncratic translations.

These small niggles apart, this is a magnificent achievement, which is unlikely to be repeated soon, and enhanced by Neil Collier’s consistently superb engineering. In addition to programme notes, full details of the organs are provided. It also makes a fitting tribute to the late Anthony Caldicott, whose tireless promotion of Karg-Elert’s music inspired this undertaking. As my colleague Christopher Nickol stated in his Gramophone review of Vol 2: ‘Stefan Engels is fully equal to the task; he’s so in tune with Karg-Elert’s varied musical personality it’s as if he was born to play this composer.’ Hear hear!