The relaxed aim of xChess is to cause the opponent to resign or capture the opponents King.
This is similar to traditional "Check Mate" which stops short of the capture move, but in xChess the opponents King may actually be captured to win, and may be captured from a "non-check-mate" scenario. A player may resign if they deem that they are facing a check-mate scenario.
Any move that threatens to capture the opponents King in the next move may be announced as "Check", but is voluntary. It remains good form and gamesmanship to announce "Check".
The capture of a King, or resignation by a players, is announced as "xChess" by the winner.