I Have No Words & I Must Design By Greg Costikyan http://www.costik.com/nowords2002.pdf
The Art of Computer Game Design By Chris Crawford https://directory.vancouver.wsu.edu/sites/directory.vancouver.wsu.edu/fi...
Playing Fair: A Look at Competition in Gaming By Mark Newheiser http://www.strangehorizons.com/2009/20090309/newheiser-a.shtml