Chess for Two on One Phone, and the Fog of War Variant

How two people play chess on one phone

Lay the phone flat between you. By default Twofold splits the screen in two halves and turns the far half round, so each player sees the board from their own side and moves their own pieces with a tap. White moves first. Tap a piece to see where it can go, then tap the square.

Chess rules the app plays

• Take turns moving one piece. Checkmate wins: the other king is in check and has no way out.
• Stalemate is a draw: the player to move has no legal move and is not in check.
• The game is also a draw by threefold repetition, by 50 moves with no capture or pawn move, or when too few pieces remain for either side to give checkmate.
• You can castle, capture en passant and promote pawns. When a pawn reaches the far side, you choose the piece it becomes.

Can you play chess with a clock on a phone?

Yes. Before the first move you can switch the clock off or give each player 5, 10 or 15 minutes for the whole game. The clock starts after White's first move and runs only for the player to move. A player who runs out of time loses.

Is chess on one phone free?

Twofold is free to download, and each game is free to play once. After that you can buy a game on its own, or all games in one purchase, including games added later. The App Store shows the price in your currency.

Fog of War chess

Fog of War is chess where you only see part of the board. You see your own pieces and every square one of them could move to this turn. The rest of the board is fog, and an enemy piece shows only when it stands on a square you can see.

Fog of War rules in Twofold

• A pawn sees the one or two squares ahead of it, and sees the squares diagonally ahead only when an enemy piece stands there.
• There is no check and no checkmate. Capture the other king to win. You can move into danger without knowing it.
• A player with no moves at all loses.
• Castling works as usual, except the king may pass through attacked squares. En passant and promotion work as in chess.
• After each move you pass the phone. When your opponent takes one of your pieces, you see which piece it was and where. That is all you learn about their move.
• The same clock options apply: off, or 5, 10 or 15 minutes each.

Why Fog of War suits one phone

The board you see differs from the board your opponent sees, so the phone has to be hidden from the wrong player. Twofold shows a cover between turns. The player whose turn it is taps Reveal to see their own fogged board, and the cover returns when they pass the phone.

What is a Fog of War chess variant?

It is chess played with hidden information. In the usual chess rules, checkmate ends the game. In Fog of War, capturing the king ends it, since you may not know your king is attacked.

Play it on one phone

Twofold plays Chess and Fog of War on one phone, with a board for each player.

Download Twofold on the App Store

More two-player games on one phone: see all games, Liar's Dice, Four in a Row.