This is an expansion on a response to +Teo Tayobobayo's probably somewhat hyperbolic post on the Google+ Fate Core community, where he said he thought Fate Core was the Grand Unified Theory of Gaming. At least in spirit I tend to agree with him.
I'm not particularly fond of game systems for their own sake. This doesn't mean that I don't like fiddling around with mechanics, but I don't have the energy or patience to deal with game systems that require too much work. The systems that are actively uncooperative and fight against what I want to do are straight out. That leaves a large swathe of game systems that I just don't care if I never see again (Exalted, every flavor of d20, GURPS, HERO), and a small gray area of games that work just okay (Silhouette, Interlock, BRP, earlier versions of Storyteller, Synergy) and I could either take or leave.
What makes Fate Core a huge deal (for me) it it makes want to roll up my sleeves, dig in up to my elbows, and do something with it. That's what a game should do...make you want to play it. t's like getting that first real Lego set for Christmas, that has a bunch of different shaped pieces and spinny thingies and rounded pieces and not just primary colored bricks. Fate Core sparks my creativity and makes me want to see what I can build with it. Tribe 8 was the last setting to really do that for me, and honestly Basic D&D was the last game.
In between those two, I've trudged a fine line between being in love with the idea of gaming but not being super enthusiastic about the process. At no point while I was completely in awe of Exalted's setting did I feel the same about the system - it was, "Do I have to use this?". Even as much as I love Tribe 8's setting, the system was more of, "Meh, I already know it so I might as well use it."
Just that get-me-out-of-my-seat reaction to Fate Core is enough of a game changer for me. But it's also unified my thinking toward roleplaying games in general. The headspace that Fate Core resides in for me carries across to any game I can imagine myself participating in. A lot of Fate's underlying principles are so broadly applicable that it has become a game that I think nearly everyone should read if only for the experience. It's turned me somewhat evangelical about the whole thing - which might be good or bad, because I'm sure some people are getting sick of hearing nothing but "Fate Fate Fate Fate" out of me.