Co Up (Hidden Xiangqi)
Chinese Chess with face-down pieces that reveal themselves as they move.
How to play Co Up
Co Up (Cờ úp, "face-down chess") is a popular Vietnamese way to play Chinese Chess. The board and the generals are the same, but the other 15 pieces of each side are shuffled and placed face-down on the usual starting points. Nobody knows what they are, not even their owner. Red moves first.
Goal
Checkmate the enemy general, or leave your opponent with no legal move.
Face-down pieces
- A face-down piece moves like the piece that normally starts on its point. On a chariot point it moves like a chariot, on a horse point like a horse, on a soldier point like a soldier, and so on.
- After its first move the piece is turned face-up. From then on it moves as what it really is.
- If you capture a face-down piece, only you see what it was. Your opponent does not find out.
How the pieces move once revealed
As in Chinese Chess: the general stays in the palace, the chariot moves in straight lines, the cannon jumps one piece to capture, the horse moves one straight and one diagonal, and the soldier steps forward (and sideways after the river). This site uses the common Vietnamese rule for advisors and elephants: once face-up they are free. An advisor steps one point diagonally anywhere, and an elephant moves two points diagonally anywhere and may cross the river. The elephant can still be blocked by a piece on the point in between.
Turn by turn
- Tap one of your pieces. Glowing dots show where it can go.
- Tap a dot to move. A face-down piece flips over when it lands.
- You may never leave your general in check, and the two generals may not face each other on an open line.
End of the game
Checkmate or having no legal move loses. The game is a draw if the same position appears three times, or after 120 moves in total with no capture and no piece turned up. Press Letters to show K, A, E, H, R, C and P instead of Chinese characters.
Strategy tips
- Count what is left. Each side has 2 chariots, 2 cannons, 2 horses, 2 elephants, 2 advisors and 5 soldiers. Keep track of what has turned up to guess what is still hidden.
- Flip from strong points. A face-down piece on a chariot or cannon point can travel far on its first move. Use that reach before you know what it is.
- Guard your general. Your advisors may be anywhere, so your palace is often weak. Keep a piece or two near the general.
- Hidden pieces are targets. A face-down piece cannot defend in an unusual way and may be a chariot. Capturing one often pays off.
- Free elephants are dangerous. A revealed elephant can cross the river and attack. Watch the diagonals near your general.
Co Up (Hidden Xiangqi) FAQ
Is Co Up the same as Jieqi?
They are close cousins. Jieqi (揭棋) is the Chinese version of hidden xiangqi. Co Up is the Vietnamese version, where revealed advisors and elephants may move freely over the whole board.
Does the computer know what the hidden pieces are?
No. The computer only knows what you could know in its place: the pieces that have turned up and the ones it has captured. It plays the odds by trying many possible deals of the hidden pieces.
Why do pieces reshuffle when I press Undo?
Undo takes back moves, but the pieces that become face-down again are shuffled among themselves. Otherwise you could peek at a piece and take the move back.
How strong is the computer?
Easy makes loose moves and is good for learning. Medium thinks for about a third of a second. Hard thinks for close to a second and weighs many possible hidden layouts.
