You don't play the ANS synthesizer with a keyboard. Instead you etch images onto glass sheets covered in black putty and feed them into a machine that shines light through the etchings, trigging a wide range of tones. Etchings made low on the sheets make low tones. High etchings make high tones. The sound is generated in real-time and the tempo depends on how fast you insert the sheets.
This isn't a new Dorkbot or Maker Faire oddity. It's a nearly forgotten Russian synthesizer designed by Evgeny Murzin in 1938. The synth was named after and dedicated to the Russian experimental composer and occultist Alexander Nikolayevich Scriabin (1872–1915). The name might not mean much to you, but it illuminates a long running connection between electronic music and the occult.