This is more of a pedagogical patch than a fully featured one. That said, it does have some sophisticated MIDI controller detection and setup using javascript.
But the heart of this is 8 rows of 8×1 step sequencers all synced to the transport object, each with independent timing control, and all interactively controlled with the matrixctl object. Anyone who wants to get into step sequencing in Max will do well to pull this apart. It simply uses General MIDI synth sounds by default, but it’s designed to make it easy to send the triggers to your own sound makers.
It’s designed to work with the Livid Code, block, and Ohm64 MIDI controllers, but there’s no reason it can’t be adapted for others.
As a bonus, I’m so nice, I even did an old-school Max 4 version!

How did this project use Max?

The project IS a max patch. That's how!