White: Rin Kaiho 7-dan
Black: Otake Hideo 6-dan
Komi: 7 points
The game was played in Rin's house in Setagaya, Tokyo, on 23 February 1964.
1-11
The first point to note is that the fuseki after move 4 looks just like a 19x19 fuseki. The second point is that there is also room to play a standard joseki as in the upper left.
12-24
There is even room so that the fuseki adage of "approach on the widest side" applies with White 12.
Rin commented that if Black 13 had been at 14 he would have simply answered at A.
He also indicated that he had considered, as an alternative to White 18, 1 in Diagram 1, which erases Black's moyo. This diagram suggests that moyos and running fights are also part of 15x15. The reason Rin did not play this way was that he decided to bask in the large komi and play quietly. He would have been unlikely to play this way on a 19x19 board.
Diagram 1
Otake thought Black 21 was the first difficult point of the game. He was tempted by B instead. He was also contemplating Black 23 at 1 in Diagram 2 but decided he didn't like White's invasion of his then flimsier side position.
Diagram 2
Yet another alternative for Black 23 he looked at was 1 in Diagram 3, but he rejected that because of White 2 and 4. Otake felt that around here his play was definitely influenced by the size of the board.
Diagram 3