Hidden information: Cribbage

[donkirkby]

Add support for games with hidden information. Is Cribbage a good one to start with? Test against single-purpose players, like cribbageksi, dacarlin's, or MCTS-Cribbage. Should we add chance elements first, like Backgammon? Something simpler, like Gin, Whist, or 31?

[donkirkby]

Here's a possibly useful paper on chance elements in MCTS.