Jesse Freeman released the artwork of two games for free.
zombies game
<img src="http://jessefreeman.com/wp-content/uploads/2012/12/rr-image002.png" border="0">
Astronaut game
<img src="http://jessefreeman.com/wp-content/uploads/2012/12/jet-image001.png" border="0">
They have the "Do What the <img src="smileys/smiley35.gif" border="0"> You Want to Public License" :)
I hope you find it useful.