This is an Inform 7 project.  Open the "Last Day of Summer.inform"
directory in the IDE; it will complain about the missing Skein, but
you can ignore that.  You may need to install the following

Default Messages by Ron Newcomb
Neutral Library Messages by Aaron Reed

You can download them from: http://inform7.com/write/extensions/

Before releasing, use "Import into Skein..." to import the file
walkthrough.rec, then label its final knot with "***".  This will be
used for "release along with a solution".

This program is copyright © Doug Orleans 2011-2012.  It is distributed
under the terms of the GNU Affero General Public License (AGPL) 3.0.
See the file COPYING for details.  The code is available from the
BitBucket Mercurial repository: http://bitbucket.org/dougo/ifcomp11