Copyright (c) 2004 David Jagger
This game is played in the following 7x8 square board:
- DROP PHASE - Initially, each player drops his King into an empty cell.
- MOVE PHASE - On each turn, a player must move a friendly piece or a group of friendly pieces (called a tandem move).
- Soldiers slide orthogonally over a line of empty cells (like the chess rook).
- Kings move to an adjacent orthogonal empty cell.
- Traps - A piece between two enemy pieces (the three forming an orthogonal line) is trapped and cannot move by its own.
- However, a piece can make a move passing thru two enemy pieces without being trapped (unless it stops its movement exactly between those two enemy pieces).
- Tandem move - a rectangle of friendly pieces (including the King) may slide as a single soldier (all pieces move as if they were a block).
- A tandem move may include trapped pieces, unless all pieces are trapped.
- Capture - Any piece not adjacent to an empty cell, and adjacent to at least to enemy pieces, is captured and removed from the board (so, a player may commit suicide, capturing his own pieces).
- Mole drop - If a player surrounds an area in such a way that the adversary cannot move pieces into that area (this structure is called a city) then the adversary may, in his turn, drop any non-trapped piece into an empty cell inside the city.
- GOAL - Wins the player that captures the enemy King or stalemates the adversary.
- If not capture is made after 50 turns, the game is a draw.
A trap example
If he moves d2-d5, he traps the three green stones at c5,d6,e5.
Some tandem moves
Black tandem moves: d567-d3 (i.e., moves the line of three stones two cells south), f5g5-h5
Green tandem moves: cb3-f3, fgh3-d3, f3g4-d3 (i.e., the square of four green pieces moves two cells west).
A capture example
By moving fgh5-c5, he will capture three green stones (namely c6,d6,e6).
A city and a mole move
Black has a city, so Green may use a mole move. He selects one friendly piece (say e1) and drop it at b6. With this move, Green is able to capture the soldier at b5 and opens a gap into the black city.
Some words of the author: Chogo can be played on many other boards [...] For Chogo on fuller or bigger boards the tandem movement of a part-trapped contingent is different. A part-trapped column can move together one space orthogonally only. On the larger boards, Chogo can (and perhaps should) be tried allowing the king to move with unrestricted rook power. Other (untested) variants might allow the trapping of not just one but more than one man, by flanking either end of connected straight lines of enemy men. [...] Also, a different rule could be adopted when a side's men are all in secure structures: "a player cannot both start and end his move with all his men in secure structures" [...] It is quite possible that forms of Chogo could be developed on hexagonal (and even other) grids, incorporating other forms of 'phasic' immobilization/capture. Finally you might like to experiment with beginning the game with an empty board, and having an initial phase where men are successively dropped onto the board - captures might or might not be allowed in this phase - with the kings being dropped last (or perhaps without kings). [...] Such a game naturally begins to resemble Go.