Cyclix is one of the 'Atlantis triplets' that employ different implementations of the 'atlantis effect', the gradual disappearance of the playing area, eventually leaving one king or the other without refuge.
The other two are Shakti and Caïssa.
In the initial position the board is covered with 49 tiles. There are two players, white and black. Each has a king, a rook, a bishop and a knight, initially positioned as shown.
- Though tiles are removed during play, all play is on the tiles. Pieces may move over squares without tiles, but may not land on them.
- With the exception of the king, pieces may take the tile they occupy along with them to a square that doesn't hold a tile.
- White moves first, then turns alternate. A player who can move must move. A player who cannot move must forfeit his turn.
- A king under attack is said to be 'in check' A king may not move in check and must lift it immediately by moving out of check, interposing a piece, or capturing the attacking piece.
- A captured piece is removed from the board and returned to the owner, who is then said to have the piece 'in hand'. A piece in hand may conditionally be re-entered, see 're-entering'.
- The king is an old acquaintance from Shakti: it moves to the first tile it can see in any of 8 directions. If and when the king moves, the tile it vacates is either removed, or it sprouts a piece the player has 'in hand', see 're-entering'.
- The rook moves and captures like a rook in chess.
- The bishop moves and captures like a bishop in chess.
- The knight moves and captures like a knight in chess.
A 'piece in hand' may be optionally re-entered. This is done by moving the king and placing the piece on the tile thus vacated. If the king moves without re-entering a piece, then the tile it vacates is removed in the same turn. There are two conditions under either or both of which the king may not re-enter a piece:
- If the king makes a capture.
- If the king moves out of check.
To checkmate the opponent's king.
Stalemate doesn't exist, 3-fold is a draw.