Hm, that TN story reminds me of something that happened during a Mouse Guard campaign where I was playing. And I think it speaks to a very real issue that RPGs always have, which is “your mental model isn’t my mental model”.

We’d wound up in a cave with a bunch of crabs scuttling around, and I announced my intention to try and climb up and sneak around to see if I could find something. The GM dropped the difficulty number, and it was astronomical. I was boggled, but he explained why–and given how he was imagining the scene, I could see why he assigned that high of a difficulty to the action.

Then he invoked “No Weasels” on it.

I did get him to back down by making some points (especially “um, so, you totally didn’t describe the bit where the cave was pretty much covered with crabs who were all looking around”). I’m not sure how to solve that central problem, because I agree–having some hidden information can make the mechanics really interesting! It just needs some assurance that the difficulty values won’t go above a certain value, I think. (It’s like how in Blackjack, you can be 100% certain that there’s no card that adds 20 to your total.)