GOMOKU Gomoku Live uses one rule for both colors. Exactly five consecutive stones win. Six or more in a row do not win. There are no forbidden moves.
Practice this opens the position on the play page with you as Black against the computer. The computer answers after your move. Diagrams are drawn for this page; row numbers and column letters match the 15 by 15 board. If you still have an unfinished online match in this browser, the site keeps that match instead of loading the lesson.
Exactly five wins
Five Black stones in an unbroken horizontal, vertical, or diagonal line win at once. In the practice position, G8 through J8 are already Black. K8 makes exactly five. F8 would also make exactly five. The game stops on that move, so you never continue the same line to six.
Six in a row is not a win
A line of six Black stones on row 8, from E8 through J8, does not win on this site. The win check looks for a line whose length is five, not five or more. Those six stones are still on the board, and the game is not over because of them.
Open the practice board to see the same position in the real game. It does not declare a winner. You can still move. Do not copy advice that treats a longer line as an automatic win. That is a different rule set.
Practice the six-in-a-row positionNo forbidden moves
Renju is a different game built on five-in-a-row. In common Renju rules, Black is the first player and is restricted: some double-threes, some double-fours, and an overline of six or more are forbidden for Black. White is not restricted in the same way. Renju also uses special opening procedures.
This site does not use those restrictions. The move below is a double open three. Black already has F8 and G8, and also H6 and H7. Playing H8 makes the row F8–H8, with E8 and I8 empty, and the column H6–H8, with H5 and H9 empty. Two open threes at once are legal here for Black and for White. The move is not a win yet, because neither line is five.
There is also no forbidden overline to play or to avoid, because six does not win and it is not a foul. Either player may place a stone on any empty intersection.
If you are reading a book or a video about Renju, check whether a move it calls illegal is only illegal for Black under Renju. On this site that move is allowed, and a line of six still does not win. The short rule on the rules page is the same rule; this page is the side-by-side comparison.