Davey Wreden is best known as the creator of The Stanley Parable (and later The Beginner’s Guide), both of which we all should have played by now. It’s hard to find much information about his life pre-Parable, since as far as I can tell it was his first real game project. Thus it’s hard to talk about how he got a start making games – there was really only one game that propelled him out of obscurity and into the spotlight.
That being said, here’s how The Stanley Parable got made: Davey was a student at USC, which is one of the top schools for game creation/design. He had been musing about unexplored areas of game design, having recently realized how innovative games could be. He was interested in narrators, and came upon the question: what if you could disobey the narrator of a game? Davey didn’t know what would happen — what COULD happen, so he decided to try to make a game to find out. The result was the original Stanley Parable mod for Half-Life 2, found here: http://www.moddb.com/mods/the-stanley-parable
Eventually, a Saxxy-winning modder named William Pugh saw The Stanley Parable mod and contacted Davey with a bunch of ideas and mockups. They continued kicking around ideas with the idea that if the game was fun for them to make, it would be fun for someone to play. The finished product ended up being one of the first games aproved for Steam via the Greenlight feature, and it has since won numerous awards/titles.