RedQuark Logo Welcome to!
This is home to the apps created by Mark A. Durham for the Apple® iPad, iPhone®, and iPod touch® mobile digital devices.

Currently available for all devices:

Engel's Enigma: A circle puzzle game related to permutation theory, group theory, the 15 Puzzle, and the cube puzzle of Ernő Rubik.

Engel's Enigma


Available exclusively for the Apple iPad:

Rings of Saturn: A game app for 1 to 4 players. Be the first to guide all five of your ships through the rings to your base at the center.

Rings of Saturn


For all inquiries concerning these apps, please email Mark A. Durham at or click here to visit the forums. pages Copyright © 2010-2013 Mark A. Durham is an independent website and has not been authorized, sponsored, or otherwise approved by Apple Inc.
“Apple”, “iPhone”, and “iPod touch” are registered trademarks, “iPad” is a trademark, and “App Store” is a service mark of Apple Inc.