A rational game becomes very useful (and sane) when its rules are founded in observation (that is to say, it's empirical). That's science. And basically all of our "crafts" (cooking, carpentry, gardening...)

That could spell the difference between sane rational games and crazy rational games right there. That presence or absence of empirical grounding.

And on the flipside, we are all familiar with games that are rigorous, with good logical consistency, but founded on thin air. Dogmatic religion, videogames, fiction...