The king is the only piece in chess that can never be captured. If a king is attacked, it is in "check". The player must move the king out of check or block the attack. If the king cannot escape check, the player loses the game.
As this is three player chess, the king can remain in a "stalemate" position (represented by "SS") when there are three players. If a stalemate occurs when only two players remain, the game is over.
King movement is limited to one square in any direction including diagonals
The king movement is blocked by any piece, including friendly pieces. This means the king can never be moved as an opening move
A player cannnot perform any move to intentionally put their king in check. Notice how F10 is not a valid move in this scenario
It is possible for a King to be taken in three player chess if there are 3 players remaining. In this example: The White Pawn takes the Red Pawn, leaving the Red King in check by the Black Queen. If this occurs the black queen has the option take the red king