Crossings is a two-player abstract strategy board game invented by Robert Abbott.
The rules were published in Sid Sackson's A Gamut of Games.
Crossings was the precursor to Epaminondas, which uses a larger board and expanded rules.
A group is a series of one or more same-colored stones adjacent to one another in a line.
(diagonal, horizontal, or vertical) A stone may belong to one or more groups.