bocch Glossary

kairo · November 1, 2026

These are the terms used in the bocch articles and in the video series "bocch定跡研究" (bocch Opening Lab). Opening moves have the same name whether Black or White plays them, as long as the shape is the same.

Basic terms

Number

The number of stones on the 8 squares around a stone (either color, up to 4). It is exactly how far that stone can move. It changes with your moves and with your opponent's.

Loner

A stone with no neighbors at all, with the number 0. It can't move.

Far row / arrive

The opponent's edge row is called the far row, and getting a stone there is called "arriving". Get two stones there and you win.

First arrival

Getting your first stone across before the opponent does. In AI-vs-AI games, the side that arrives first wins about two-thirds of the time.

Reach

A stone that can arrive on the far row next move, or that situation.

Gap

The number of rows to the far row minus the stone's current number. Gap 0 is a reach. Gap +1 is a stone whose number is one too small, and gap −1 is one too large; either one becomes a reach when a single stone next to it moves.

Names of opening moves

Corner Guard

Moving an edge stone one square straight forward.

Snuggle

Sliding an edge stone diagonally forward so it sits next to its neighbors and its number goes up. For Black, 1f→2e or 6f→5e.

Shoulder to Shoulder

White sliding an edge stone diagonally forward. It is the same shape as Black's Snuggle, and it is considered almost always the best second move for White.

Lone Spear

Moving the second stone from the edge two squares straight forward.

Migrating Bird

Jumping over a neighbor to go diagonally toward the center.

Drifting Cloud

An inner stone slipping out diagonally toward the edge.

Frontal Breakthrough

Moving a center stone two squares straight forward.

Strategies

The combination of your own first and second moves is called a "strategy", and the 10 most common ones have names. They are introduced in How the New AI Changed Opening Theory, and 10 Strategies.

Twin Walls

After the Snuggle, slide in the other edge stone as well, bringing both edges inward.

Shield & Spear

Build a shield with the Snuggle, then push the stone beside it straight out with a Lone Spear.

Escort Bird

Send the stone beside the Snuggle flying diagonally with a Migrating Bird.

Shapes and tactics

Tower

Four stones packed into a square in a corner of the board (for Black, 2e, 3e, 2f and 3f). Every stone keeps a number of 3–4 and can jump far.

Invasion

Jumping all at once to just in front of the opponent's home.

Push-up

A way to stop a reach: put your stone next to the opponent's reach stone to raise its number so it jumps past the far row.

Pull-away

A way to stop a reach: move your stone away from beside the opponent's reach stone to lower its number so it falls short.

Blocking the landing square

A way to stop a reach: put a stone first on the square the opponent wants to arrive on. It looks natural, but the opponent's number doesn't change, so they can easily find another landing square.

Backfire

Changing an opponent stone's number with your own move and turning it into a reach. A "landing backfire" happens next to your landing square, a "leaving backfire" next to your starting square. → Article on backfires

Wake-up

Landing next to an opponent stone that is a loner, so that it can move again. Sometimes played on purpose. → Article on the Poisoned Bun

Draw-back

Pulling a stone that has advanced back toward home, to raise the numbers of the stones behind.

Home wall

Stones left in your own home blocking the opponent's landing squares and serving as defense.

Attack and defense in one

A move that stops the opponent's reach and creates a reach of your own at the same time.