Objective of the Game

Renju is a strategic board game for two players. The aim is to form an unbroken row of five stones of your own color, which can be horizontal, vertical, or diagonal. The game uses the same grid board as Go, typically 15x15 in size.

Game Components

• A 15x15 grid board
• Two types of stones, typically distinguished as black and white.

Setup

• The board is initially empty.
• One player selects black stones, the other selects white stones.
• The player with the black stones always goes first.

Gameplay

1. Turn: Players take turns placing one of their stones on any unoccupied intersection on the grid.
2. Black Stones: The player with black stones must be the first to make a straight line of five stones.
3. White Stones: The player with white stones will also aim to achieve this, while having the advantage of counteracting black's moves more tactically.
4. Differing Strategies: Black stones come with certain rule-based restrictions to balance their offensive advantage:
5. No multiple threes or open fours: Black cannot create double-three (two separate lines of three) or get open four formations, which could potentially offer multiple winning options.

Special Rules

• Five in a Row Rule: Only an unbroken line of exactly five stones of the same color wins the game. Lines longer than five do not count as a win.
• Black has Restrictions: Due to the inherent aggressive potential black offers, the rule restrictions on creating double threes or open fours ensure a balanced gameplay.

Winning Conditions

• The first player to form an unbroken line of five of their own stones wins the game.

Strategy Tips

• Black: Focus on occupying strategic positions early without breaching the forbidden formation rules. Position yourself to force White to constantly defend rather than advance.
• White: Make use of defense advantages to prevent Black from making headway. Plan complex defensive and offensive strategies to shift the momentum in your favor.

Renju requires foresight and strategic thinking, as you need to either successfully block your opponent or force them to give up by blocking necessary moves consistent with winning.