I hope nobody minds that I post my suggestions although I have no time to participate:
@ Blink:
You could start a thread to collect riddles which fit with your story, if you don't find enough time to develop these on your own.
Just a thought.

http://www.puppenheim.org/
http://www.wuerfels-welt.de
Old Game Tutorial: http://www.puppenheim.org/MITutorial.zip
Free Game Editor: http://puppenheim.org/AlienalsWeihnachtsmann.zip
http://www.puppenheim.org/blender_starting_main_settings.txt