alien-night.jpg - Rob Cosgrove <abug@ozemail.com.au>
kraftwurm.jpg - Qwertz <kraftw@gmx.de>
fulmine.jpg - Andrea Rizzi <rizzi@kde.org>
mystical_rightturn.jpg - Christian Müller <cmue81@gmx.de>

License: free for commercial and noncommercial usage, distribution and
modification

The following tiles are courteously provided by  Bowie J. Poag / PROPAGANDA:

Superfluous-Organ-1.jpg, The-Good-Times-1.jpg, Whirling_Spirit.jpg,
Appropriately-Left-Handed-2.jpg

License: Copyleft