My actual playing experience consisted of a D&D game DMd by my Dad when I was 13. I DMed a couple of games of FASA Star Trek because nobody else in my little clique of "friends" knew jack about rpgs. Those were unsatisfying, because I take my roleplaying too seriously and none of my clique took it seriously at all. Actually, my Dad probably felt the same way about me when we were playing...

My current preference for 3e GURPS with a lot of House Rules and a bit of 4e thrown in here and there probably mitigates against me getting another game together ever again.

Mostly, I read a lot of supplements and build a lot of worlds, and generally imagine what it would be like to travel through those worlds. When I'm writing, I occasionally game out snippets of action to work out, in detail, just how things could be done and just how improbable success might be. Thus a fairly "realistic"...ish system like GURPS.

Whether for actual gamers or for armchair game-readers like me, rules-light world supplements are very attractive. Go for it!