I like microtuned pianos, but they're hard to do.
There's an ongoing pull request on the sfizz .sfz player, to support MIDI Polyphonic Expression. One feature of MPE is that you can convert fractional values into an integer note value plus pitch bend. Since each note plays on its own channel, pitch-bend applies per note rather than globally. (sfizz also supports Scala files, but this is different -- it lets you go full Jacob Collier on your sub-sub-sub-semitones. MPE's default settings allow for 1/170th of a semitone pitch resolution.) sfizz works a treat with spacechild1's fantastic vstplugin~ external.
So, if you're comfortable compiling software yourself, you can have fractional notes on a sample player. sfizz was a relatively painless build in Linux. "git clone --recursive" from https://github.com/rullopat/sfizz-ui .
Here's what might have happened if Ligeti had an eighth-tone piano:
Initially, I had tried to use [poly] for voice/channel assignment. It got confused about so many notes so close together, so I ended up making my own version that binds the note number to the channel and duration.

hjh


