Choose your stone
How to Play
Choose Your Mode
Play versus AI at Easy, Normal, or Hard. Optional 2 Players mode uses the same device.
Pick a Side
In vs AI, choose Dark (goes first) or Light (goes second).
Place a Stone
Tap or click any empty intersection on the 15×15 star grid. There are no captures.
Get Five in a Row
Align five of your stones horizontally, vertically, or diagonally. Freestyle rules — no renju restrictions. A full board without a winner is a rare draw.
Captain Tips
Create Two Threats at Once
If you set up two open-ended fours simultaneously, your opponent can only block one. That is the fundamental winning pattern.
Open Threes Beat Closed Threes
A row of three with both ends open is far stronger than one blocked at one end. Prioritize open-ended extensions.
Attack From Both Sides
Extend a row from whichever end the opponent is not defending.
The Centre Controls the Board
Stones near the centre participate in more potential five-in-a-rows than edge stones. Do not let the AI claim the central lines unopposed.
Why Play Cosmic Gomoku?
Deep Threat Building
Simple to learn, hard to master. Force unblockable doubles and outpace the AI on a spacious 15×15 grid.
Mobile Ready
Tap an intersection to place. The board and controls are sized for phones and tablets as well as desktop.
Always Free
Challenge the AI in your browser. No downloads, ads, or paywalls. Freestyle Gomoku — no renju rules.
Frequently asked questions
- Is Cosmic Gomoku free to play?
- Yes. Cosmic Gomoku is completely free in your browser — no downloads, registration, or payments required.
- Can I play Cosmic Gomoku on mobile?
- Yes. Tap an empty intersection to place a stone. The board and controls are sized for phones and tablets.
- Can I play Cosmic Gomoku against the computer?
- Yes. Choose vs AI and pick Easy, Normal, or Hard difficulty.
- Does Cosmic Gomoku use renju rules?
- No. Cosmic Gomoku uses freestyle Gomoku on a 15×15 board — five in a row wins with no renju forbidden-move restrictions.
