Language, history and curiosities in games.
Those who do not play do not live. Those who do not playtest do not design.
How can you design a car without driving it? Or how can you make a movie without watching it? This is the same thing. How can you design a game without playing it?
I recognise good playtesters by my (frequent) urge to strangle them.
You can make (most) designs interesting through your play-talk—but when published, your design needs to speak for itself.
Of course, I do a bit of sports and I read, all the natural things. But there isn’t a big pastime where I need to flee from the world. I am already in my own world, in the rich world of games.