You know that something is amiss when even my wife can figure out the problem with an RPG...
I bought the Fate Core System book (Evil Hat Productions) not too before heading off to EOW and have been reading it intently every since. It is not a complicated game per se, just one that take a lot of things that are relatively unspoken or hand-waved in RPG's and builds the rules around them.
I don't want to get too deep into the rules in this post, but rather just look at the pivotal one: Aspects. Aspects are akin to the Distinctions in Marvel Heroic Roleplaying. Actually given the timeline, MHR ripped off FUDGE/Fate. But since I knew MHR first, I have to work from what I know. In MHR, if you do something that dovetails with one of your Distinctions, you can either get an additional d8 (if it is positive) or a d4 and a Plot Point if it suggests a negative occurrence. So for example if you use "Highly confident" to do something smoothly because, well, you think you can, you get a d8. If you say "Doctor Mind is doing something foolish he shouldn't because he's overconfident," you get a d4+PP.
Onto Fate. Aspects are also descriptors of your PC, his background, personality, or nature. But you can't invoke them anytime the story makes sense, you have to use a Fate point, and then you get a noteworthy bonus or a re-roll, either of which likely will mean success for the die roll. You have a limited supply of Fate points, but can garner more by invoking your Aspect in a negative manner (called a "compel") which essentially means you are tanking the roll or generally doing something stupid or foolish or just plain badly that will create drama for the storyline. In the above example about Doctor Mind, if he was in Fate instead of MHR, he wouldn't even roll in the latter case, he would just automatically screw it up because he was over his head.
This works, I think, when you have players who don't mind having their PC's fail from time to time. That means that you can't use this with a group of players indulging in adolescent power fantasies who complain vocally every time they get hit or fail to damage something. (I'm not saying that's my group, I'm saying that's a lot of people's groups, however.)
Also possible, and what my wife twigged to (after I had done the same) is that obstinate players could deliberately tank inconsequential moments (negotiating for the cost of new armor, etc.), rank up on Fate points, then use them in critical moments. A GM would have to be on guard about those kinds of shenanigans.
It also seems to me to be a game intended for four or fewer players. I could see people continuing throwing points around ensuring that everything that must happen does. That'd be frustrating. Of course, I've yet to find a game that actually works well with a large number of players...
More later, although I do have a thought: Gamma World Fate.