Here’s a new idea I have, inspired by my rule for Go Zendo, which I can now happily share without spoiling that game
You start with a common shape consisting of two stones.
Black and White will play a normal game of Go, consisting of two stages. In the first stage, the players are forbidden to create the shape with any of their opponent’s stones.
They keep playing like this up to the point that neither player has a possible move left. Then stage 2 starts, and the players can finish the game without restrictions.
As an example of a shape, let’s consider the Knight’s Jump:
In our example, that means that during the first stage, Black is not allowed to play on any intersection that would be a knight’s jump away from a White stone, and vice versa. Stage two starts when neither player can make a move.
I’ll simulate an example game:
Assuming 6 komi, White wins by 1 point
What happens if one player has no more possible moves, but the other player still has available moves that they don’t want to play? For instance, maybe my only possible moves are playing inside my own territory or worse, filling my own eyes.
I guess this can depend on the shape. With a knight’s jump or a one-space jump, it seems quit hard to be forced to kill your own group, but with an iron pillar it seems basically impossible not to kill yourself.
Let’s say that one doesn’t have to play all available moves, as long as the other player has already run out of valid moves.
It would also seem quite natural to let both players pass whenever they want, and after two consecutive passes the game moves to stage 2. But perhaps you specifically wanted to see some tactics involving force-filled eyes
If these shapes are in relation to the opponent’s stones, it’s rather the other way around!
Edit: Never mind me, I forgot that the rules are forbidding those shapes, not forcing you to play those shapes.