The piece in the center region of the board is called the Neutron and neither side owns it. The goal is to move the Neutron to a square in your own back row. In Co-Neutron, the goal is to move the Neutron into your top row.
 
All pieces move in the same way, in a straight line in any direction. A piece must move as far as it can in one direction; it continues until it is blocked by a wall or another piece. There is no capturing.
 
 
Neutron was invented by Robert A. Kraus and published in issue 71 of the English magazine `Games & Puzzles` in July/August 1978. Italian players E. Neri and R. Baldassarri analyzed the 5x5 game as a win for White, and recommended playing on the 7x7 board. Mark Owen and Julian Richardson of Cambridge University suggested a reversed version of Neutron, which they call CoNeutron, in which the object is to get the Neutron to your opponent's back row (or to stalemate the opponent as usual).
 
Board pieces are set-up randomly in this zrf.