Beyond the Planet of the Apes was created with Inform and has IFID 26070430-E25A-43B7-B917-A0051B2262B9. 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.
Or you can play without downloading anything by following the 'Play In-Browser'
link, using the Quixe interpreter. You'll need to have Javascript enabled
on your web browser.