Game.exe will run the game in a standalone window. However, if you don't want to or can't run it, it is also possible to run the game locally in a browser with some effort.
Simply opening index.html in the www folder will likely not work; instead, you must run the game using localhost.

A simple way to start a localhost session is by using Python. Download and install it here.
https://www.python.org/downloads/

Once Python is installed, open Command Prompt or equivalent (Terminal in Mac OS).

Navigate to the game's "www" folder. (Example: cd "C:/Users/Default/Desktop/YourTurnToDie/www")

Enter this command to start a localhost server based in the current directory:
python -m http.server
It should show a message like "Serving HTTP on [IP address] port [number]..."

Finally, open the following URL in your browser.
http://localhost:8000/
(The port number it tells you should be 8000 by default, but if it's not, replace "8000" in this URL with that number.)

You should keep the server console running while you play, and can close it once you're done.

NOTE: When playing this way, save data will be stored in your browser's Local Storage for "localhost:8000" (or whatever the port is), rather than as files in the "save" folder.