I've been designing games for as long as I can remember.
I love everything about game design: the challenge of coming up with original gameplay mechanics, working out algorithms that give the desired result, writing the story, designing the characters, scenarios, stages, playtesting, refining, etc.
Below are some examples of games that I have designed, as well as a few sample game design documents.
Here's an early version GDD for a casual game:
The Piggy Cute Game
Here's an old Game pitch I put together a number of years back, which is fairly similar in layout to a typical design document:
Nintendo DS Puzzle Pack