This program was released under the GPL and thus the sourcecode is here and available for you to download!
You can obtain the newest and most updated version from github from the Club-Ubuntu sponsored version (Paradox Edition) here:
Sorry but currently the source is in a ... lackluster... state use "old script"
http://github.com/teamcoltra/Choose-Your-Own-Adventure
You may also view the older (mildly kept-up) SVN Repo:
https://svn.iamcal.com/public/www/choose/