# What's the least amount of pieces on an Othello board where black or white can't make a move?

Say you're following the traditional rules of Othello. What is the least number of pieces possible on the board, producing a result where one of the two players(black or white) can't make a move, thereby passing play to the other player?

What is the least number of possible pieces on the board where both players can't make a move, therefore ending the game before the grid is completely filled?

Bonus question: An othello game can end with the board being entirely filled all one color. Is it possible for all the pieces on an Othello board to be one color, but the board isn't filled entirely? If so, can you give a sequence of moves that would result in that outcome?

• For the first question, does it need to be a situation that can arise in a real game of Othello or we can just lay the pieces however we want to set up that situation?
– Hai
Nov 19 '17 at 10:03
• It has to arise out in a real game of othello. Same with the second question. Nov 19 '17 at 16:53
• Otherwise the problem would be ridiculously easy. Nov 19 '17 at 21:50
• Interesting question! Related: boardgames.stackexchange.com/questions/20539/… Nov 21 '17 at 21:13
• I think "fewest number" is more appropriate than "least amount." Nov 24 '17 at 14:27

For the bonus, the shortest possible game that results in all pieces the same colour (9 moves) is here: https://www.youtube.com/watch?v=6ehiWOSp_wk

D3C5D6E3B4C3D2C4F4 which is the same sequence Julia gave, not only answers the bonus question, but actually all questions. The least number for both players to not have an option is the 9 move wipe out, so 13 discs including the starting discs. It also is the answer to the first question, unless you want to say "one player of the two players can't make a move but the other can". In that case the sequence would be quite a bit longer. I remember someone posting a sequence to a very early pass and if I recall correctly the pass was in the early 20's.