If someone were to say, right now, that I have played my last game and I will never again play a game, I would be more than a slight distressed. It is my most prevalent hobby. However, if I still get to watch the evolution of arguably the most interesting medium since the invention of the written word, I think I would manage. If someone were to say: you get to have time-travelling, but you lose gaming, I'd do it in a heartbeat, just to see where it would go in the future.
Because games are my obsession. Gaming isn't. I want to see what is going to happen next in the fastest-growing medium ever. Graphics, mo-cap, storytelling, gameplay. They're all improving! And I just want to be there to witness it. This is why I like games so much. They're a unique form of entertainment, and it's constantly changing.
I game a lot, too, for two reasons: first of all, it's just for fun. It's a fun hobby, which can be competitive or relaxing, aggravating or soothing. There aren't as many movies that piss me off as there are games, but there aren't as many that can captivate me as much either.
The reason I spend so much time with games is because it's both. An obsession and a hobby. But I'd give up the second for the first in a heartbeat.