So it goes.
* A square board with an odd number of squares per side (at least 7x7)
* Enough Reversi pieces to fill the chosen board
The player with the most pieces with their color turned up wins the game.
The first player plays a black piece onto any square. The second player may choose to either place a white piece onto any other square or switch colors with the first player.
Play then proceeds as follows:
* Players place one piece per turn onto any unoccupied square.
* If the placement forms a palindrome with any connected pieces side-to-side, up-and-down, or diagonal, bounded by empty squares or edges then all of the pieces in the palindrome are flipped to the color played.
* If a flip causes the formation of another palindrome then the new palindrome is also flipped, if that too forms a palindrome then it too is flipped, and so on.
When the board is filled, or the players mutually agree then the game ends and the score calculated.
The rules and example diagrams for Othel Lehto are also available online at http://fogus.me/fun/spiel/combinatorial/othel-lehto/.