A Dragaeran game involving squares drawn on the ground (or floor) onto which black and white stones in various states of roundness or flatness are dropped.
Stakes are apparently wagered on how close or far stones land relative to a specific target. It is also possible to use your stones to knock an opponent's out of position. (Similar to Bocce, or Marbles.)
The name is apparently shortened from "Sivalli-Yangorra stones".
"A quick game, boss?"