I first came across Nikolais's work quite by chance back in the early 2000s, when the East Village apartment block complex over the road from us had its annual stoop sale. Not expecting to find anything of interest in a cardboard box crammed with sad, shabby looking LPs, I stumbled upon an album of Nikolais's "choreosonic music of the new dance theatre", going for $1. The cover sent an electric shudder of anticipatory excitement through me.
The cross-pollination of avant-classical music and avant-garde ballet has a long tradition, but unusually - possibly uniquely - Nikolais created his own electronic and musique concrete scores for his work. He also devised the startling light design, the costumes and wigs and bizarre head-gear, and every other component of the spectacles he staged - which as I write in the 4:3 appreciation, "hovered somewhere in-between ballet, kinetic sculpture, avant-garde fashion, and ritual ceremonies from the far future or from some alien civilisation".
Here are some examples Nikolais's work, including this recreation of "Tensile Involvement" for the opening sequence to Robert Altman's twilight-era film The Company (the movie heads sharply downhill after this, let me tell you).
Update: Andrew Parker points me to this bizarre film, for which Nikolais did the choreography
How are you all doing out there / in there? Slowly going barmy as time turns mushy.