Cation, a connection game built on ko

[luigi]

I have just designed Cation, a square board connection game where crosscuts are resolved with a ko rule of sorts.

In the past, I have designed a few other square board connection games that are well worth trying, like Vimbre and Quentin, but I think this one is my best, and it probably wouldn't exist without Go.

Here is what perfect play looks like on a 4x4 board:

Cation.- Sample 4x4 game 2.png (37.83 KiB) Viewed 13954 times

Note that at a center point instead would lead to a Black win, but the text is arguably optimal with the pie rule in place as it leads to the longest perfect play sequence.

[hyperpape]

I think I'm missing something. On the third move on the bottom row, why can't Black connect and win?

[luigi]

I think I'm missing something. On the third move on the bottom row, why can't Black connect and win?

Because that would create a crosscut containing a stone (c1) that was placed by the opponent on their latest turn, which is illegal.

From the rules:

a) There are no crosscuts on the board. In this case, you must place a stone of your color on an empty point of the board such that it forms no crosscuts containing a stone that was placed by the opponent on their latest turn. If there is no such placement available, you must pass. Passing is otherwise not allowed.

The game doesn't work well without this condition (it's too cold).

[luigi]

Here's a typically close, 94-move sample game on an 11x11 board.