Sustain pedal. Not sure how it’s implemented in midi, but that’s one way to have more than ten notes playing at once. (There’s also four-hand duets and the rare

Sustain pedal. Not sure how it’s implemented in midi, but that’s one way to have more than ten notes playing at once. (There’s also four-hand duets and the rare but not non-existent play two adjacent white keys with one finger technique.)