Play Like Designer part1 :http://penny-arcade.com/patv/episode/playing-like-a-designer-pt.-1
Play Like Designer part2:http://penny-arcade.com/patv/episode/playing-like-a-designer-pt.-2
Don't Know what is mechanics :http://penny-arcade.com/patv/episode/narrative-mechanics
All reference and link from: Penny Arcade - Extra Credits