Puzzle would have played while the player solved slower-paced puzzle rooms. These would yield items to access jumping challenges, combat rooms, and other puzzles that would eventually lead to the unlocking of a boss door.
As an example, the first puzzle involved using a limited number of items to weigh down pads that would reveal stairs and doors.
This track is somewhat more calm than the others, and perhaps a bit melancholy, which suits it well to puzzle-solving. It's one of the only tracks to use an instrument outside of the YM2413 sound bank - a generic square wave that is used quite prominently throughout the song. An echo effect is also used heavily in this song.