There are a lot of good game books out there; I will only list some of them here for you to read:
Challenges For Game Designers at http://www.amazon.com/Challenges-Game-Designers-Brenda-Brathwaite/dp/158450580X
Game Design at http://www.amazon.com/Game-Design-Bob-Bates/dp/1592004938
Level Up! The Guide To Great Video Game Design at http://www.amazon.com/Level-Up-Guide-Great-Design/dp/047068867X
A Theory of Fun for Game Design at http://www.amazon.com/Theory-Game-Design-Raph-Koster/dp/1449363210/ref=pd_sim_b_4?ie=UTF8&refRID=0RF5R20HCRGDSR4JEY0N
Game Feel: A Game Designer's Guide To Virtual Sensation at http://www.amazon.com/Game-Feel-Designers-Sensation-Kaufmann/dp/0123743281