Source code by David Thompson <davet@gnu.org> - GPLv3+
Sprites by David Thompson <davet@gnu.org> - CC BY-SA 4.0 International
KenPixel Mini font by Kenney - CC0 - http://opengameart.org/content/kenney-fonts
Music by Juhani Junkala <juhani.junkala@musician.org> - CC0 - http://opengameart.org/content/5-chiptunes-action
Sounds by Little Robot Sound Factory <www.littlerobotsoundfactory.com> - CC-BY 3.0 - http://opengameart.org/content/8-bit-sound-effects-library