The game can is played on a 9x9 Go board with 18 pieces to each side, one unique piece among the 18.
From Zillions of Games:
Forces are arrayed on the second and third rank with the marked stone at the center of the third. The unmarked stones are know as Hoplites and the marked stone is the Enomotarch.
All stones move the same:
Step one to two vacant points forward orthogonal,
- or -
Push an opposing stone located adjacent right or left orthogonal to the next right or left vacant orthogonal point,
- or -
Leap over any number of adjacent friendly stones forward, right or left orthogonal to a vacant point.
- or -
Capture an opposing stone on an adjacent forward diagonal point.
The game is won by capturing the opposing Enomotarch, or moving the friendly Enomotarch to any rank beyond the opposing forces.