Free Online Sea Battle Game — No Download | Playgridia
Looking for a free online sea battle game? Naval Battle on Playgridia is the pen-and-paper grid fleet duel you remember, plus three things paper never had: a firing pattern that changes with the ship class, one signature ability per hull, and fog that keeps your notes for you. No download, no install, no sign-up — it opens in the browser and a match is over in a few minutes.
What is different from the paper version?
The core feeling is identical: you fire into your opponent's waters and the pattern of hits and misses walks you onto their ships. What changed is how much information a single turn carries.
| Pen-and-paper version | Naval Battle | |
|---|---|---|
| Board | A hand-drawn grid, usually 10×10 | 10×8 = 80 squares, one map (Open Sea) |
| Deployment | You place the ships yourself | The server places both fleets at random, no setup screen |
| A shot | Always a single square | 1, 2 or 3 squares depending on which ship fires |
| Hit chain | House rule: hit and shoot again | None — the turn passes even on a hit |
| Extra weapons | None | One signature ability per ship, on a cooldown |
| Note-keeping | You mark the paper | Every square you fire at leaves a permanent mark in the fog |
| Opponent | Whoever is sitting opposite | A friend by link, or a bot at three difficulties |
Free actually means free here
Naval Battle runs in the browser: the same game on a phone, a tablet or a desktop. You do not have to create an account — a guest session behaves like a full one, collects coins and streaks, and can be linked to Google later. And there is nothing to unlock in this game: it ships one map, Open Sea, and everybody has it, so you will never meet a locked board, a ticket or a season wall here.
The fleet: four ships, fourteen cells
- Carrier (5 cells) — fires a single square; Air Strike bombs a 3×3 block of nine squares, once every five of your turns.
- Battleship (4 cells) — a 3-square horizontal broadside; Heavy Bombardment is a 2×2 salvo, once every four turns.
- Cruiser (3 cells) — a 2-square line; Cross Salvo hits a 5-square plus, once every three turns.
- Destroyer (2 cells) — a single square; Torpedo Run hits the square you choose and the one directly below it, once every three turns.
Cooldowns are counted in your own turns, so your total ability budget for a match is small. And damage is not a debuff: a carrier with four of its five cells burning still calls a full 3×3 strike. Only sinking a ship takes its weapon off the board.
A turn takes ten seconds
You tap enemy waters; the strongest gun you still have afloat is picked for you and locks the target. The strip at the bottom names the ship, the shot and the square; you confirm, it fires, the turn passes. Tapping one of your own hulls opens only that ship's ability — the one menu in the game — and ships never move. Every turn asks a single question: where do I fire?
Two players, three bots
To play a friend, open a table and send them the link; if nobody is around, a bot is always ready. The Easy bot fires completely at random and never uses a signature ability — the right opponent for learning the rules. Medium and Hard sweep around a hit, search on a checkerboard pattern and spend abilities on confirmed contact; Hard simply does it faster.
The maths of searching: 14 cells in 80 squares
The enemy fleet covers a little under a sixth of the board, so a blind shot into open water misses about five times out of six. On paper there is only one way to beat that: the checkerboard trick. Because the smallest ship is 2 cells long it must always cover one light and one dark square, so sweeping a single colour — 40 shots — is guaranteed to touch every hull.
Here there is a faster route. While your battleship is afloat the broadside opens three squares even at the edge, so a 10-square row costs four shots (columns 1, 4, 7 and 9) and the entire 80-square ocean is checked in 32. That has a consequence worth knowing: sinking the enemy battleship does not just cost them 4 hull cells, it also halves their search rate. Decisions like that are the whole subject of our strategy guide.
Winning, scoring and the clock
Sink all four enemy ships to win. Your score is how many you sank, 0 to 4, so a 4-0 and a 4-1 are not the same victory. The move clock is a room setting between 20 and 600 seconds, 30 by default. Running it out does not lose you the match — only that one turn is played by a fog-aware bot — and a dropped connection keeps your seat, with the handover reversed the moment you come back.
For the full rules see our how to play Naval Battle guide, and for a winning plan the strategy guide. Ready? Play free now.
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Frequently Asked Questions
Can I play a sea battle game online for free?
Yes. Naval Battle runs in the browser: no download, no install and no sign-up, and a guest session is enough to start straight away. The game ships one map, Open Sea, and everybody has it, so there is no board to buy or unlock.
How is this different from the pen-and-paper game?
The board is 10×8, so 80 squares, and the fleet is deployed at random by the server every match. A shot opens 1, 2 or 3 squares depending on which ship fires, each ship carries a signature ability on a cooldown, and the turn passes even when you hit — there is no shoot-again rule.
Can I place or move my own ships?
Neither. Fleets are deployed at random by the server and ships are fixed. Each turn you make exactly one decision: where to fire. Tapping one of your own hulls only opens that ship's ability.
Can I play against a bot?
Yes, at three difficulties. The Easy bot fires completely at random and never uses a signature ability; Medium and Hard sweep around a hit, search on a checkerboard pattern and spend abilities on confirmed contact.
How long does a match take?
The default move clock is 30 seconds and a turn is a single decision, so most matches finish in under ten minutes. In the room you can drop the clock as low as 20 seconds or raise it as far as 10 minutes.