Black MIDI is an upcoming genre of keyboard music that uses gaming and MIDI software to create keyboard music so complex, so dense, that these works, playable only by computers, have note counts that sometimes stretch into the millions. The reason it's called Black MIDI is because of the extreme density of notes when realized on staff paper.
TTC's Dream Battle is a nice introduction to the genre:
And now for the real stuff. TheSuperMarioBros2's Bad Apple boasts 4.6 million individual notes:
This work by TheBlackMIDITeam has 110 million notes:
Kinda makes learning Chant de Linos seem like a walk in the park.
More Black MIDI links: