I discovered that Wits and Wagers was actually discussed here: http://lesswrong.com/lw/14u/wits_and_wagers/

I tried it out and it is much easier to play than my game and thus is somewhat more fun. But it also has less insights.

My experience is as follows:

• The trivia questions are not difficult enough. It is very seldom that values lie outside a times 2-range. And 'surprises' are rare.
• The questions have an american cultural bias (no wonder)
• The 'going over' rule is simple but totally skews the betting and guessing.
• The simple payout-rules cause gaming for higher payouts thus mixing confidence and probability in non-trivial ways.
• The two-phase setup where you can look where the 'experts' bet is interesting but doesn't help with confidence calibration.

It really is optimized for playability. I think it does some calibration of (over)confidence and it builds intuition for probability and risk-trade-offs.

But - and that is my main point - it doesn't have clear concepts. The concepts are all mingled up, skewed, hidden. You may gain intuition but it will not help you toward overcoming e.g. overconfidence bias or egocentric bias.

I still think for that the concept must be sufficiently present to be able to reflect and consciously use it.