Freestyle gomoku: first to five wins
Freestyle is the simplest version of gomoku (omok, five in a row). Black moves first, players alternate, and the first to line up five stones horizontally, vertically or diagonally wins. Neither color has forbidden points, and forks like 3-3 and 4-4 are fair game for both.
Rule sets disagree on whether six or more in a row, an overline, counts. Some versions require exactly five, but Playfulo's freestyle mode counts five or more as a win. Under Playfulo's default rule you never need to worry about overlines.
The simplicity comes at a cost: Black's first-move advantage is large. Freestyle gomoku on 15×15 is a proven win for Black with perfect play, and even between equal humans Black tends to win noticeably more. In friendly games it is fair to swap colors every game.
Renju: three bans for Black only
Renju was designed to reduce Black's edge. Black is not allowed to play on points that create certain shapes, called forbidden moves. White has no restrictions at all and may play 3-3, 4-4 or an overline freely.
Playfulo's casual renju mode follows this principle and bans double-three, double-four and overline for Black only. Tournament renju also adds opening rules that fix how the first few moves are chosen; the casual mode focuses on the forbidden-move rules.
- Double-three: Black creates two or more open threes with one stone
- Double-four: Black creates two or more fours with one stone, including two fours on the same line
- Overline: Black makes six or more stones in a row
- Four-three is allowed: a four plus an open three is legal for Black
- White is unrestricted: 3-3, 4-4 and overlines are all legal for White
Why forbidden moves exist
In gomoku, moving first means attacking first. If Black keeps creating threats from move one, White spends every turn defending and eventually falls to a 3-3 or 4-4. Forbidden moves remove Black's two easiest finishing blows and narrow the gap.
Black still keeps the 4-3, which is a powerful weapon. So renju does not stop Black from winning; it forces Black to design sharper attacks built around fours. Renju is also believed to be a theoretical win for Black, which is why tournaments add opening rules to rebalance it further.
How strategy changes for Black and White
In renju, Black has to find finishing sequences that end in a 4-3 while avoiding 3-3 and 4-4. Points where two open threes would cross become useless, so Black learns to prepare one line as a four and another as a three, meeting at a crossing point. Even a VCF must be checked so the last move is not a double-four or an overline.
White's defensive burden becomes lighter. Since Black cannot play 3-3, White can worry less about two threes forming and focus on Black's fours and potential 4-3s. White can also counterattack with 3-3 and 4-4, giving White more options than Black.
An advanced White technique is forcing Black into a forbidden point. White builds a four whose blocking point happens to be a 3-3 or 4-4 for Black. Black is not allowed to play there, so the four cannot be stopped. Good Black players manage their shape so that forbidden points do not appear where they may need to defend.
How to recognize a forbidden point
The double-three is the trickiest ban. Only real open threes count, meaning threes that can actually become an open four on the next move. A three that is already blocked on one side, or whose only path to an open four runs through another forbidden point, does not count toward a double-three.
A double-four is forbidden whatever its shape. It covers fours on two different lines and also a single line with two winning points, such as X X X _ X _ X X X. For an overline you simply check whether the move makes six or more in a row.
Under official renju rules, a move that makes exactly five wins even if it also creates a forbidden shape. Forbidden-move detection is complex and implementations can differ in edge cases, so on Playfulo's renju mode the on-screen notice and whether a point is selectable are the reliable guide. Playfulo does not let Black place a stone on a forbidden point.
- Step 1: Imagine Black's stone on the point and scan all four directions: horizontal, vertical and both diagonals.
- Step 2: If any direction reaches six or more stones, it is an overline.
- Step 3: If two or more lines would become five on the next move, it is a double-four.
- Step 4: If two or more open threes that can reach an open four appear, it is a double-three.
- Step 5: If the move completes exactly five, official rules count it as a win regardless of other shapes.
Common mistakes when switching rules
Players moving between freestyle and renju repeat the same errors. A quick check of this list before a game prevents easy losses.
- Planning a 3-3 finish as Black in renju: the last move is banned and the attack collapses.
- Thinking the 4-3 is forbidden: it is legal for Black and is renju's main winning tool.
- Only defending as White in renju: White has no bans and can counterattack with 3-3 and 4-4.
- Not checking whether Black's blocking point is forbidden: if it is, Black cannot block White's four.
- Keeping fixed colors in freestyle: Black is heavily favored, so alternate who goes first.
Which rule should beginners start with?
If you are new to gomoku, start with freestyle. Without forbidden moves to track, you can focus on learning open threes, fours, 4-3s and 3-3s, and build an intuition for why certain shapes are strong. Playfulo uses freestyle as its default for this reason.
When basic threats start jumping out at you and you win most games as Black, move on to renju. It demands more precise attack design from Black and rewards White for using forbidden points, which makes it excellent reading practice. On Playfulo you choose freestyle or renju when starting an AI game or creating a room for a friend, so try both rules at the same difficulty and feel the difference yourself.