Gonu is a family of games. This variant is played on an 4x4 board with the following setup:

MOVE - A stone moves to an orthogonal adjacent empty cell.
A move cannot be made that repeats any previous position.
CAPTURE - Capture is custodian, i.e., if a stone, after moving, has some enemy stones between itself and another friendly stone, then those stones are captured.
GOAL - A player looses if he has just one stone (unable to capture) or is unable to move.

An example

White soldier at b4 moves to cell [1], capturing the black soldier at c3. Black does not have good moves. If b2-b1, then b3-b2, and stalemating Black on the next move.

There is a ZRF to play Jul-Gonu with Zillions.

Seo SangHyeon (which implemented the ZRF) says: Jul-Gonu is a type of Gonu, which is one category of Korean traditional board games, usually played on a board hand-drawn on the ground and with distinguishable stones, so it can be easily played without any equipments. The name of this game 'Jul' means 'line', for the board is drawn with lines. There are many variants due to regions. They differ in the size of the board, the number of stones, the initial position, etc. ... Jul-Gonu can be played on board larger than 4*4, but it's tiresome. Custodian capture is not the essence. It's all about parity and forced retreat. And the larger the board, the easier players can avoid repetition and just playing inside his territory. It's considered 'no manner', but rule to prohibit this is tricky.