Look at these

Really in depth theories on game play from Mike Lopez at Gamasutra

http://www.gamasutra.com/features/20061128/Lopez_01.shtml


A good article on game character design with the legendary games designer Shigeru Miyamoto

http://www.gamasutra.com/features/20020308/saltzman_01.htm

An interview with David Goosen on mobile game design

http://www.gamasutra.com/features/20060307/cifaldi_01.shtml

An interesting article on how mobile gaming will develop in the future

http://www.gamasutra.com/php-bin/letter_display.php?letter_id=1318