Background used for educational fair use. Original can be found here: https://www.artstation.com/artwork/43OQW Spaceships used for educational fair use. Originals can be found here: http://millionthvector.blogspot.com/2013/01/free-spaceship-sprite.html http://millionthvector.blogspot.com/2013/07/new-free-top-down-spaceship-sprite.html
