That's coz all the music is MIDI files :) they're very light.
This maybe also explains why the sound doesn't play on certain platforms.
Yes there is also a bunch of wasted space in making dungeons made of separate rooms and rooms that only serve as routers, lol.
(I think I know how that game is so small. It is even more amazing when one by accident x6’s the source code file size.)
;-)
And yes Midi has a bug allowing for arbitrary code execution due to its format so it broke stuff. Removing the midis is.... on a to do list. One that will be never touched.