checkmate

Word called out by the victor when making a move that wins the game.

Said when one has placed a person in a losing situation with no escape.

The conclusive victory in a game of chess that occurs when an opponent's king is threatened with unavoidable capture.

This immediately ends the game, provided that the move producing the checkmate position was in accordance with Article 3 and Articles 4.2 – 4.7.

Any losing situation with no escape; utter defeat.

To put the king of an opponent into checkmate.

My opponent checkmated me in four moves!

The game is won by the player who has checkmated his/her opponent’s king.

To place in a losing situation that has no escape.

Where is it? What does SCP-3125 look like? Its motivation, its origins, its modus operandi— how much of that can be known? Does it have to be known, to solve the problem? Does it matter how intelligent the intelligence is, once it's inside the box, once it's checkmated?