intricate

All large drawers have puzzles inside. You will need to solve these puzzles to open other drawers or find secret compartments.

Adjusting these pegs on the back of the memory board changes the tune it reads. The dark pegs represent the notes of the song.

A secret button opens the center of the desk revealing a checker pattern. If you find a way to rearrange it into a key pattern the center drawers unlocks.

Source