Robin Hunicke studied "dynamic difficulty adjustment in games" as a graduate student at Northwestern University. During her studies she worked on a mod for Half-Life that adjusted the game's difficulty based on the player's performance before Left 4 Dead's AI Director became a thing.
After a conversation with Will Wright at a conference, she decided to make the jump into the game industry, designing expansion packs for The Sims and becoming the lead designer on MySims. She's best known for her work with thatgamecompany as the Executive Producer for Journey. She's currently the co-founder and CEO of Funomena working on a mostly-unannounced commercial game.
What drives her is her desire to create games that elicit feelings from the player. She recently spoke at Humlab in Sweden about a concept she calls "Feeling-First Games." The short version of it tasks independent developers with building games centered around the desired emotional outcome of the game instead of building games around which mechanics you want to use (is it a shooter, a racing game, etc).