Because you won't hear any of the sound effects or music if you play online.
To download the files you'll need and get the game started, follow A, B and C below:
A. Use this link to download the zipped Six game bundle for any OS (9.1 MB)
The bundle includes the story file Six.gblorb, the PDF manual, Demi’s map of the park and the cover art. If you haven’t played Interactive Fiction or text adventures before, the manual is for you.
B. To run the story file, you’ll need to download a free Interactive Fiction Interpreter for your OS.
Below I list four interpreters suitable for playing Six (list last updated 7 September, 2022). They're listed in order of suitability for this game by operating system, so just read down the options and download the first interpreter you encounter that will work for you:
C. Unzip and/or installl the interpreter you just downloaded, then open the story file (Six.gblorb) in it and play!
You can start the game either by OPENing the file Six.gblorb from within the interpreter, or perhaps by dragging and dropping Six.gblorb on the interpreter app.