Fog of war chess is chess with hidden information. You see your own pieces and the squares they can reach; the rest of the board, and most of your opponent's army, is covered by fog. Nobody announces check, and you win by capturing the enemy king.
The rules in 30 seconds
- The pieces move as in classical chess, and White moves first.
- You always see your own pieces, plus every square they could move to or capture on. The rest of the board is fog.
- An enemy piece shows up only while it stands on a square you can see.
- There is no check. Nothing warns you that your king is attacked, and moves that leave it attacked are allowed.
- Capture the opponent's king to win.
What each piece sees
A square is visible to you when one of your pieces could move there or capture there right now. Your own pieces are always visible.
- Rook, bishop and queen see along their lines up to the first piece in the way, and that piece too, whether it is yours or the opponent's. Nothing behind it.
- Knight sees all the squares it could jump to, even over other pieces.
- King sees the eight squares around it.
- Pawn sees differently: it only sees where it could actually go. See how pawns see.
Vision changes with every move. When a piece moves away, the squares it was watching go back into the fog, and an enemy piece you saw a move ago may be somewhere else by now.
How pawns see
A pawn sees only the squares it could move to:
- one square straight ahead, if that square is empty;
- from its starting square, two squares ahead, if both are empty;
- nothing straight ahead when the next square is taken: a blocked pawn doesn't see what is blocking it;
- a diagonal square only when an enemy piece stands there, ready to be captured.
A pawn that suddenly can't move is information: something is standing right in front of it.
No check: capture the king
The game never tells you that your king is attacked, and it never stops you from making a move that leaves it attacked. The king is captured like any other piece, and capturing it ends the game. There is no checkmate: a king that is attacked but not taken is still alive, and the attacker has to actually take it.
Because walking into an attack is never illegal, keeping the king safe is your job: castle early, keep defenders around it, and keep count of the enemy pieces you haven't seen for a while.
Castling, en passant and promotion
- Castling is allowed when the king and that rook haven't moved and the squares between them are empty. Unlike classical chess, you may also castle while your king is attacked or across an attacked square, and nothing will warn you.
- En passant works as in classical chess.
- Promotion: a pawn that reaches the last rank becomes a queen automatically.
How a game ends
- You capture the opponent's king: you win.
- A player resigns.
- A player runs out of time. Games are played with a clock.
- A stalemate is a draw.
When the game is over the fog lifts, and you see the whole board and where everything really was.
Fog of war chess vs classical chess
| Classical chess | Fog of war chess | |
|---|---|---|
| What you see | The whole board | Your pieces and the squares they reach |
| Check | Must be dealt with straight away | Doesn't exist, nobody is warned |
| How you win | Checkmate | Capture the king |
| Castling | Not out of, through or into check | Allowed even under attack |
| Promotion | Queen, rook, bishop or knight | Always a queen |
| What wins games | Calculation | Calculation, memory, deduction and bluff |
Tips for your first games
- Castle early. A king hidden behind its pawns is hard to find, let alone catch.
- Use pawns as scouts. Every step forward lights up new squares.
- Respect the knight. It strikes from squares you can't see, without any warning.
- Keep your pieces defending each other. A lone attacker deep in enemy territory is usually a gift.
- Be suspicious of free pieces. In the fog, an undefended piece is often bait.
- Remember where you last saw enemy pieces. Pawns never change files without capturing, so their files are the most reliable trail.
- Trade for information. A capture deep in enemy territory gives your piece a look around from there.
Where the game comes from
Among chess variant players the game is known as dark chess. Jens Bæk Nielsen and Torben Osted invented it in 1989 while playing a correspondence game. It builds on Kriegspiel, the 1899 variant in which neither player sees the other's pieces, but with a simpler rule: each player sees what their own pieces see. Online it became widely known as fog of war chess.
Fog of Chess is built only for this variant: ranked games, bots to practise against, games with friends and knockout tournaments.
FAQ
Is fog of war chess the same as dark chess?
Yes. Dark chess is the original name from 1989; fog of war is the name most players know it by today. Small details can differ from site to site, and this page describes how the game works on Fog of Chess.
Why is there no check?
Announcing check would tell you where an invisible attacker is. Without it, the king can be captured, and capturing it is how you win.
Can I practise against the computer?
Yes. Fog of Chess has bots that get stronger each time you beat one, so you can learn the rules before playing people.
Can I play with a friend?
Yes. Create a room and send your friend the invite link.
Is it free?
Yes. Fog of Chess is free and runs in your browser, with nothing to download.
Where else can I play fog of war chess?
Chess.com has it among its variants, and PyChess hosts it too; Lichess doesn't have it. See where to play fog of war chess for how the sites compare.