Diamond Mino.

How it goes together

This is a complete Mino, gold still on 5h, with the left silver added on 4g. Getting it there is the whole difficulty, and it is a rule rather than a preference: a silver cannot step sideways, so it can never walk 5g to 4g. It has to come down onto 4g from 5f. So the silver takes the long way round, 7i, 7h, 6g, 5f, and only then drops into place behind the 4f pawn.

The base is a plain Mino, all seven moves of it, and the silver is walked over afterwards.

Move by move

Black only, from the start position. The Mino first, then the ordinary ranging rook development that puts the left silver on 6g, and then that silver’s walk to 4g.

Four generals, every one of them covering the king or the square in front of him. Thirteen moves, and both silvers are defenders now.

What it is good against

Almost everything, for as long as it stands. Two golds and two silvers around one king is more defence than any castle outside the corner, and a piece dropped anywhere near it is simply taken. Against an attack that has already started, the diamond is the shape a Mino player runs to.

Where it breaks

The clock, and the piece count. Thirteen moves is most of an opening, and the silver that walked over is a silver that is not attacking, so a game against a Diamond Mino often turns on whether the other side got a real attack going first. Above the king it is no better than a plain Mino: 2g is still bare and the edge is still the edge. The crown is what fixes that.

When to build it

When the opponent is committed to attacking your castle and you have the moves to answer. It is a defensive choice rather than an opening plan, and the left side of the board goes quiet to pay for it.