For me it is mainly a journey to discover what is possible with interactive media. Storytelling is what interests me the most, especially how it combines with game mechanics.
I love the fact that in a game, differently from a film or a book, you are part of the world and not only a point of view. You can interact with the world, change the world and see what the consequences are. You can create living, breathing worlds you can explore. This is the thing that excites me the most about this medium.