My homework for http://www.reddit.com/r/learngameprogramming/ as username 'shotintheface'.

Solutions are written in Guile Scheme 2 using guile-SDL and are not written to be portable.

This code, like guile-SDL, is published under the terms of the GNU General Public License, version 3 or later. See COPYING for detail.

To obtain a copy of guile 2, please visit http://www.gnu.org/software/guile/ as it may not have been packaged for your linux distribution yet. I also recommend you use the copy of guile-sdl from http://github.com/downloads/ijp/reddit-learngameprogramming/guile-sdl-bt.tar.gz as there hasn't been a release since 2009.

Thanks to openclipart.org for the image "monster_01.png" which is released under the CC0 Public Domain Dedication. See http://www.openclipart.org/about and http://creativecommons.org/publicdomain/zero/1.0/ for details.