I have two suggestions on how to improve play on custom board sizes:
- Enable custom board sizes in tournaments.
- Add star points to 11x11, 23x23, et c.
Star points are problematic when the board is even or when the width is not equal to the height, but a possible algorithm is:
- Only consider boards where the width is equal to the height and the width is uneven.
- Only place a star point on tengen for boards <= 7x7.
- Place star points on 3-3 and tengen for boards <= 11x11
- Place star points on 4-4 and tengen for boards >= 13x13.
- Place star points on 4-4, tengen and sides for boards >= 19x19.