How to Play Stone Flick & Gomoku

1. Goal of Stone Flick

The objective of Stone Flick is clear and straightforward: knock every one of your opponent's stones off the board. The first player to eliminate all opponent stones while retaining at least one surviving stone of their own on the board wins the match.

2. Board and Stone Specifications

EGO ARENA translates the proportions of a traditional 19-line Baduk board into a 2D physics coordinate system, rendered with vivid 3D board visuals.

• Board Dimensions: With the grid line spacing set as 1 unit, the board's width and length are 19.6 units, featuring an outer margin of 0.8 units from the outermost grid line to the wood edge. The coordinate space spans from 0 to 19.6.
• Stone Dimensions: Each stone has a radius of 0.46 units (diameter 0.92 units). When a stone's center point crosses outside the board boundary (less than 0 or greater than 19.6), it is ruled out of bounds (out).
• Stone Formations: Choose from 5 stones (Quick Match), 7 stones (Standard Match), or 10 stones (Master Match). Black (moves first) and White (moves second) face each other in point-symmetric starting formations across the center.

3. Launch Controls (Drag and Release)

EGO ARENA supports both mobile touch screens (smartphones and tablets) and PC mouse controls.

1. Select a Stone: When your turn begins, tap or click one of your stones on the board (a red ring highlights valid stones for the active player).
2. Aim and Adjust Power: Press and drag backward away from your desired launch direction. The aim trajectory points opposite your drag, and launch velocity scales proportionally with drag distance.
3. Maximum Power and Shot Cancellation: Drag distance is calculated up to a maximum of 5 units, achieving the top launch speed of 19 units/s. To cancel an aimed shot, simply release your finger or mouse within 0.3 units of the stone's original position.

4. Turn Progression and Victory

Game 1 begins with Black attacking first, alternating turns thereafter.

• Victory Ruling: The match concludes the instant an opponent's final stone drops off the board, leaving them with 0 stones.
• Best of 3 Series: When Best of 3 is enabled, the first-turn advantage alternates each game (Game 1 Black, Game 2 White, Game 3 Black). The first player to secure 2 wins takes the series.
• Simultaneous Out Rematch: If a single shot knocks the final stones of both players off the board simultaneously leaving 0 stones, a sudden-death tiebreaker match takes place with 1 stone each.

5. Three Attack Modes

When creating a room or configuring a match, choose between three attack rule sets:

• Alternate: The classic Stone Flick rule. Regardless of hit or miss, the turn passes to the opponent after each shot.
• Streak: If you knock out at least one opponent stone while keeping all friendly stones safe, you retain your attack turn and can shoot again. Missing or losing your own stone passes the turn immediately.
• Until You Slip: As long as your own stone stays on the board, you keep shooting even if you miss. However, the entire attack possession has a strict 30-second time limit; once time expires while stones are stationary, the turn passes.

6. Stone Flick Ruling Terminology

After each shot concludes, the physics engine evaluates stone positions and falls to announce precise contextual rulings.

Ddeok (stuck)

When two opposing stones come to rest tightly touching each other. Ruling criteria: distance between the centers of the two stones is 0.97 units or less (diameter 0.92 units + 0.05 margin).

Kkwaek (self-out)

A self-inflicted blunder where you knock out zero opponent stones while exactly one of your own stones drops off the board.

Double Kkwaek

A devastating double mistake where the same player commits a Kkwaek on two consecutive turns.

Double Play (Multi-Loss)

A single shot that knocks two or more friendly stones off the board, severely fracturing your formation.

Nongae (sacrifice)

A heroic sacrifice where your stone falls off the board, but takes one or more opponent stones down with it.

Two-for-One / Multi-Out

An exhilarating scoring shot where your stone stays safely on the board while knocking out two opponent stones (Two-for-One) or three or more (Multi-Out).

7. Timeout Rules

Time management and turn transition rules:

• Match Timers (vs Computer / Two-Player): Normal modes have no per-turn timer, allowing unhurried aiming. In "Until You Slip" mode, the entire possession has a 30-second time limit.
• Committing 3 consecutive timeouts is treated as an intentional forfeit and results in an automatic loss.

8. Gomoku (Omok) Rules and Forbidden Moves (3-3, 4-4, Overline)

Gomoku (Omok) is a traditional tactical board game where Black and White alternate placing stones on grid intersections. The first player to form an unbroken line of 5 stones of their color horizontally, vertically, or diagonally wins the match.

• Placement and Turn Order: Black plays first (typically starting at the center point, Tengen), and White and Black alternate placing one stone per turn on any empty intersection. Placed stones are never moved or removed.
• Renju Forbidden Moves for Black: To offset Black's first-move advantage, standard Renju rules prohibit Black from playing three types of moves (White has no forbidden moves and can also win with 6 or more stones):
  • Double Three (3-3): Black cannot play a move that simultaneously creates two or more open threes (unblocked rows of three).
  • Double Four (4-4): Black cannot play a move that simultaneously creates two or more fours.
  • Overline (6 or more): A line of 6 or more consecutive Black stones does not count as a win and is forbidden. Black must connect exactly 5 stones, using a Four-Three (4-3) fork to force a win legally.
• Playing Gomoku in EGO ARENA:
  • Board & Controls: Matches take place on the standard 19-line board (361 intersections). On PC, click once with a mouse to place a stone. On touchscreens, tap once to zoom in and show a preview stone, then tap the same spot again to confirm placement. On keyboards, use arrow keys to navigate the cursor and press Enter or Space to place.
  • Match Assistance & Visual Cues: In matches against the computer, you can undo up to 3 times per game (reverting both your move and the computer's response). A subtle dot marks the most recent move, ✕ markers indicate forbidden spots during Black's turn under Renju rules, and the winning 5 stones light up with golden rings upon victory. You can also choose a time limit (Off, 30 or 60 seconds per move); a third timeout loses the game.
  • Complete Guide: Explore detailed diagrams for forbidden moves, 4-3 winning forks, and computer play style tendencies in the Gomoku Rules & Forbidden Moves Guide.