Initially, the board has six stones on it, chosen to have all six colors and all six symbols. You place the remaining 66 stones one at a time, adjacent to existing stones, subject to the following rules.

— Adjacent to one stone, you must match the existing stone either by color or by symbol.

— Adjacent to two stones, you must match one by color and the other by symbol.

— Adjacent to three stones, you must match one by color and the other two by symbol, or one by symbol and the other two by color.

— Placing a stone adjacent to four stones creates a “four-way”. The new stone must match two of the stones by color and the other two by symbol. Creating four-ways can greatly increase your score.

The game ends when you have placed all the stones, or when there is nowhere to place the next stone.

The scoring for placing a stone is as follows:

— adjacent to one stone: 1 point;
— adjacent to two stones: 2 points;
— adjacent to three stones: 4 points;
— adjacent to four stones: 8 points.

You get no points for placing a stone in the squares along the outside edges, though those stones do help when placing future stones.

Creating a four-way doubles the above schedule, for each four-way. Additionally, four-ways get the following bonus points.

— First four-way: 25 points
— Second four-way: 50 points
— Third four-way: 100 points
— Fourth four-way: 200 points
— Fifth four-way: 400 points
— Sixth four-way: 600 points
— Seventh four-way: 800 points
— Eighth four-way: 1,000 points
— Ninth four-way: 5,000 points
— Tenth four-way: 10,000 points
— Eleventh four-way: 25,000 points
— Twelfth four-way: 50,000 points

Finally, placing all the stones gets a bonus of 1,000 points; all but one a bonus of 500 points; and all but two a bonus of 100 points.

To maximize your score concentrate on constructing four-ways. Place two stones with one shape, and two with one color, around an empty square. Then wait for the appropriate stone to fill the square. Keep track of which stones are still to come: there are exactly two of each shape and color combination. The highest score that I’ve heard of is 127,600 with 12 four-ways.

The easiest way to place a stone is to click on the destination square. A more elegant way is to click on the new stone to pick it up, then click again to place it at its destination.

In either case, you can click on the newly placed stone again to pick it up and move it somewhere else. This is true even if placing this stone finished the game.

Your current point total is displayed on the scoreboard at the right. When the game ends, you can click there to start a new game.

The bottom-right panel displays the remaining stones (not including the one you are about to place).

On an iPhone (or other i-device), use the web browser’s “Save” button and click “Add to Home Screen”. Then get out of the web browser and launch Ishido directly from the home screen. This lets Ishido use the entire display.

On a touch-screen device, like a smart phone or a tablet, the only way to move a stone is to click on the destination square — you can’t drag a stone. Also on such devices, clicking on the newly placed stone to undo the placement will make the stone jump all the way back to the holding area.

Ishido was invented in 1989 by Michael Feinberg, and the original Macintosh program was written by Ian Gilman. See Ian’s web page for more details and downloads of other versions. The “Shaman” stone set is from the original Macintosh program.

This implementation was created from scratch by me, Andrew Birrell.