I think the best hobby for gamers is reading. Whether you're reading fact or fiction, a good book stimulates and engages the brain. It's also a good way to pick up ideas, which are the currency of gaming these days. It is possible to get inspirations and ideas from other media, like TV and movies, but those media encourage the analytical brain to shut down. You have to make an effort to keep that sort of thinking going as you're watching, but the rewards can be pretty awesome.