Instructions
Navigate to "The World's Hardest Game" in your Web browser. Click "Begin," then "Play Game," then "Play Game" again.
Click the speaker icon in the lower right corner of the Windows desktop. Click "Mixer" to open Windows' Volume Mixer controls.
Click the speaker icon underneath the name of your browser -- "Internet Explorer," for example, or "Google Chrome" -- to mute it. If you're playing "The World's Hardest Game" in Firefox, click the speaker icon underneath "Plugin Container for Firefox."
Close the Volume Mixer window and return to the game in your browser. You can now play the game while listening to different music using your computer's media program or CD player.