Editing Gomoku (section)

=== Tournament Opening Rules ===
Tournament rules are used in professional play to balance the game and mitigate the first player advantage. The tournament rule used for the gomoku world championships since 2009 is the Swap2 opening rule. For all of the following professional rules, an overline (six or more stones in a row) does not count as a win.<ref name=":3" />
[[File:Swap Rule Gomoku.jpg|left|thumb|'''Swap''' Opening Rule: Tentative Black places two black stones and one white stone anywhere on the board. Tentative white chooses which color to play as.]]

==== Pro ====
The first player's first stone must be placed in the center of the board. The second player's first stone may be placed anywhere on the board. The first player's second stone must be placed at least three intersections away from the first stone (two empty intersections in between the two stones).<ref name=":4">{{Cite web|title=Opening rules {{!}} GomokuWorld.com|url=http://gomokuworld.com/gomoku/2|url-status=live|archive-url=https://web.archive.org/web/20210722164403/http://gomokuworld.com/gomoku/2|archive-date=2021-07-22|access-date=2021-07-07|website=gomokuworld.com}}</ref>

==== Long Pro ====
The first player's first stone must be placed in the center of the board. The second player's first stone may be placed anywhere on the board. The first player's second stone must be placed at least four intersections away from the first stone (three empty intersections in between the two stones).<ref name=":4" /><ref>{{cite web | access-date=2021-07-28 | url=https://www.renju.net/rule/7/ | title=Gomoku – pro rule | website=www.renju.net}}</ref>
[[File:Swap2 Gomoku.jpg|thumb|'''Swap2''' Opening Rule: Tentative Black places two black stones and one white stone anywhere on the board. Tentative White responds by picking option number three and placing two more stones, one of each color, on the board and passes the choice of which color to play as to tentative Black.]]

==== Swap ====
The tentative first player places three stones (two black, and one white) anywhere on the board. The tentative second player then chooses which color to play as. Play proceeds from there as normal with white playing their second stone.<ref name=":4" />

==== Swap2 ====
The tentative first player places three stones on the board, two black and one white. The tentative second player then has three options:

# They can choose to play as white and place a second white stone
# They can swap their color and choose to play as black
# Or they can place two more stones, one black and one white, and pass the choice of which color to play back to the tentative first player.

Because the tentative first player doesn't know where the tentative second player will place the additional stones if they take option 3, the swap2 opening protocol limits excessive studying of a line by only one of the players.<ref name=":9" /><ref name=":4" />