I think Wesnoth is a good strategy game for honing one's skills as a Bayesian. There is non-determinism in the game mechanics that require one to integrate numerous probabilistic events to be an effective player.
By posting a comment in the welcome thread you can pretty reliably get enough karma to post in the discussion section.
But do you find it annoying that other people can't post until they get karma? Do you wish there were more top-level posts by people with no karma?
(or, to make even more of a leading question, do you wish that new people who had an idea for a post but no karma didn't lurk and comment for a week or two before showing their idea?)
That was helpful, thanks! That would have been difficult for me to find otherwise.