Numbridge — Rules

Bridge

Bridge is the main variant of Numbridge: a 9×9 field with digits 1 to 9. What all the variants share — the field, the bag, the hand, the three kinds of turn and the price of a mistake — is described in the basics; this page covers only what makes Bridge different.

The goal

Each player is given a pair of opposite sides of the rhombus, and the winner is the one who first connects their two sides with a chain of their own cells.

• Blue connects the top and the bottom.
• Red connects the left side and the right side.

The chain runs through cell neighbourhood — those same six sides of a hexagon. Cells in a chain must touch side to side; a chain never goes "through a corner", because a hexagon has no corner neighbours.

It does not matter how a cell became yours: by a correctly placed digit or by a claimed given. All that matters is that it is yours.

An example

Take a small four-row rhombus for clarity. The letter s marks blue's cells. The chain starts in the top row and ends in the bottom one, each cell touching the previous one side to side: the sides are connected, blue has won.

row 1  .   s   .   .
row 2    .   s   .   .
row 3      s   .   .   .
row 4        s   .   .   .

Here there is no bridge: the cell in the third row has not been taken yet, and the chain is broken.

row 1  .   s   .   .
row 2    .   s   .   .
row 3      .   .   .   .
row 4        s   .   .   .

Note that a chain need not run straight. Six neighbours give it room to wander, and the same bridge can be completed by several different paths — which is what makes it hard to cut.

No positional draw

Fill the rhombus completely and one of the two players is bound to be connected: that is how a field with six neighbours works. So a game played to the end always goes to somebody: a position where nobody is connected simply does not exist. The same holds for Blitz: the field is smaller, the structure is the same.

A draw is still possible — but only by agreement, with the "Draw" button, as in the other games of the club. The game itself never produces one.

Hence a consequence that matters in practice: blocking your opponent builds your own bridge. A cell that cuts their chain stands on your path as well.

The pie rule

The first move of the game is worth a little something, and the pie rule evens it out. Right after the very first stone appears on the field, the opponent may, instead of their own move, take that stone for themselves — the cell changes owner and play continues as usual.

The offer does not last long: it stands only until the opponent has moved. Make an ordinary move and the pie is gone; let the clock run out so that the turn burns and it is gone as well — staying silent will not preserve the right to the first stone.

The "Take the first stone" button appears on the table only while taking the pie is actually possible.

Usual room settings

Rooms are configurable; in the club, Bridge is set up like this:

• a 9×9 field, from 22 to 34 givens, 30 by default;
• claiming a given costs one tile, and the hand is refilled afterwards;
• blocks regular or irregular — your choice in the seek;
• candidate highlighting allowed;
• 60 seconds per move, 15 minutes per game; the study room (Numbridge Study) gives more time — two minutes per move and half an hour per game — and is not rated.

A game usually takes three or four dozen moves.