You're unhorsed and disarmed, but you still have your wits and your guitar. You can only hope they'll be enough.
The Song of the Mockingbird was created with Inform and has IFID 407E5657-D5E9-4218-BE3E-3DECA658485F. To play a work like this one, you need an interpreter program: many are available, among them Zoom
for Mac OS X and for Unix; Windows Frotz or Windows Glulxe for Windows. The postcard was written by Andrew Plotkin and designed by Lea Albaugh.
Or you can play without downloading anything by following the 'Play In-Browser'
on your web browser.