The limited information about the game system in Majoru Oakheart's story may have been prompted by secrecy, but I'll bet anything that more of it had to do with the convention environment. When I'm trying out a new RPG in a four hour time block, I don't spend time trying to learn every last detail of my character sheet, or looking in someone else's copy of the books to figure out what things do. I play the GM's adventure, asking about specific things when they might be relevant, which it seems was this GM's policy. I'd be pissed as hell if I was in a group of four, none of whom were familiar with the game, and one of the other players insisted on monopolizing the GM for a half hour learning all his details. It's not like the GM hid things about how AC, attacks or saves worked. The only thing the secrecy element probably meant was that you couldn't go sit down with the GM later and look through the books together.