Setup
Each king starts face-up on e1 and e8, as in normal chess. Shuffle each side's other fifteen pieces and deal them face-down onto the rest of that side's home squares: the whole back rank except the king, plus the entire pawn rank. Neither player knows any hidden identity, including their own.
So the armies are the standard chess sets (one queen, two rooks, two bishops, two knights, eight pawns per side), but you do not know which face-down piece is which until it moves.
First moves use the starting square
Before it reveals, a face-down piece moves by the role of the square it sits on, not by its hidden identity. A piece on a1 or h1 moves like a rook. Pieces on the b and g squares move like knights, the c and f squares like bishops, and the d square like the queen. Pieces on the pawn rank move like pawns.
That first move is a normal move of the borrowed role, with all the usual blocking and capture rules. A face-down piece on a knight square can hop over pieces like a knight even if it later turns out to be a bishop.
Reveal on move
The moment a face-down piece moves, it flips face-up for both players and plays by its true identity for the rest of the game. The borrowed starting-square role is gone; from now on it moves as whatever it actually is.
This is where the surprises live. In the board below, the white piece on b1 hopped out like a knight and revealed the queen on c3, while the black piece on g8 did the same and revealed a bishop on f6. You are always reading two things at once: how a piece may move right now, and what it might turn out to be.
Pawns and promotion
A piece on the pawn rank moves like a pawn: forward one square, capturing one square diagonally. A face-down piece still on its home pawn rank may also advance two squares on its first move, both squares empty, just like a normal opening pawn. There is no en passant.
A pawn promotes the instant it reaches the far rank, and you choose the piece (queen by default). This can happen two ways: a known pawn marching to the last rank, or a face-down piece that reaches the last rank and reveals as a pawn there. Either way it promotes on arrival.
Castling
You can castle while the corner piece is still face-down, since a corner piece moves like a rook. The king must be unmoved on its home square and the corner it castles toward must hold an unmoved face-down piece. Move the king to that corner to castle.
The castle is that corner piece's first move, so it reveals as it lands next to the king. It might flip up as something other than a rook; the castle still stands. The normal restrictions apply: you cannot castle out of, through, or into check, and the squares between king and corner must be empty.
Check, checkmate, and draws
Both kings are face-up, so this is real chess check and checkmate. A face-down piece gives check using its starting-square role: you can be forced to answer a check from a piece that turns out to be a humble pawn. Once it moves it reveals, and any check from its new square uses its true identity.
Win by checkmate. Stalemate is a draw, as in chess. The game is also drawn by the fifty-move rule, counted from the last capture, pawn move, or reveal, and by threefold repetition of the public position (face-down pieces count as anonymous backs, so a position repeats based on what both players can actually see).
Captured hidden pieces
If a face-down piece is captured before it ever reveals, only the capturer learns what it was. The owner just sees one of their face-down pieces leave the board. The capturer can use that private knowledge to rule the identity out elsewhere.
What it is
Reveal Chess is an invented variant. It borrows the hidden-then-revealed mechanic from Jieqi, the Chinese game where xiangqi pieces start face-down and reveal as they move, and applies it to standard chess. The pitch is short: Fischer Random, but the arrangement is hidden and revealed piece by piece.
It is not Fog of War. In Dark Chess, positions are hidden but identities are known; here it is the reverse, the positions are fully public and the identities are hidden. Two different things are being concealed.
Where to next
Reveal Chess plays best with a friend. Send an invite and learn the shuffle together. For the base game, read chess; for the variant that inspired it, read jieqi.