A game from Quảng Nam and central Vietnam played on a 5×5 lattice with marked diagonals. Pieces are never removed: moving your piece into the gap between two enemy pieces on a line — a gánh, "carrying" — flips both of them to your colour, and the flip can cascade (vây) through a whole surrounded group.
Variant implemented
Cờ Gánh from central Vietnam: 5×5 alquerque lattice, 8 pieces each on the sixteen border points, slide to an adjacent point, "gánh" (carrying) conversion when you sandwich an enemy, plus "vây" chain conversion of surrounded groups.
Board and pieces
A 5×5 lattice with marked diagonals — the alquerque pattern.
Setup
Eight pieces each on the sixteen border points, arranged with 180-degree rotational symmetry. The inner 3×3 starts empty.
Turn
Move one piece one step along a drawn line to an adjacent empty point.
Capture and scoring
Nothing is ever captured — pieces change sides instead. Gánh (carrying): when your piece lands between two enemy pieces that are opposite each other through it, both flip to your colour. Vây (surrounding): after any gánh flips, a connected enemy group with no adjacent empty point flips too, and this cascades.
Win condition
Convert every enemy piece, or leave your opponent with no legal move.
Draw condition
A long stretch with no conversion is scored on piece count.
Special rules
Because pieces are never removed, the total on the board is always sixteen. The game is entirely about the ratio.
Computer opponent
Alpha-beta. The evaluation weights the piece ratio heavily and detects standing carry threats — empty points whose opposite neighbours are a same-colour pair.