Memory Gumoku

GAME RULES: MEMORY GOMOKU

Memory Gomoku is a highly challenging upgrade to the traditional Gomoku (Caro) game. Beyond strategic thinking to block and set up winning moves, players must utilize peak memory skills as the pieces on the board will gradually hide after a certain number of turns.

1. Basic Winning Conditions (Standard Gomoku Rules)

Board Size: Typically $15 \times 15$ (or custom configured per room).

Game Pieces: Two players take turns placing Black (X) and White (O) pieces.

Winning Condition: The first player to form an unbroken line of exactly 5 of their own pieces horizontally, vertically, or diagonally wins the match.

Note (Optional Setting): The "double-open 4" or "two-end block" rule (where a line of 5 is blocked at both ends and not counted as a win) can be toggled based on room settings.

1. The "Memory" Mechanic - The Core Twist

This is the central mechanic that creates suspense and high-stakes gameplay:

Hidden State (Fog of War): Once a piece is placed on the board, it remains clearly visible for only $N$ turns (e.g., the next 3 or 5 turns, or fading away immediately after the opponent completes their move). After that, the piece will fade out and disappear (become hidden) from the screen.

The Illusion of an Empty Board: As the match intensifies, the board UI may look completely empty, but the previously played pieces are still active and hidden underneath.

Spatial Memorization: Players are forced to remember:

The exact positions of their own pieces to continue building a 5-in-a-row chain.

The exact positions of the opponent's pieces to block them in time.

1. Special Placement & Overlap Rules

Since the pieces are hidden, specific rules handle what happens when a player accidentally tries to "overwrite" an existing piece:

No Overlapping: Players are not allowed to place a new piece on a square that is already occupied (regardless of whether that piece is currently visible or hidden).

Illegal Move Penalty:

If a player selects a square containing a hidden piece, the system will trigger an error (e.g., device vibration or an on-screen warning).

The Penalty: That player forfeits their turn immediately (the turn passes to the opponent). Alternatively, it counts as a foul. Exceeding the maximum allowed fouls (e.g., 3 fouls) results in an automatic Match Forfeit (Loss).

1. Turn-based Timer (Time Pressure)

To maintain a fast-paced game and prevent players from stalling to recall the board state:

Turn Timeout: Each player has a strict time limit per move (e.g., 15 or 30 seconds).

If the countdown timer reaches zero before a piece is placed, the player loses their turn, or the system automatically places a piece on a random empty square (depending on backend configuration).