History of Checkmate

Checkmate is a triumph for completing the secret chess puzzle in the Unknown Space.

How to complete

1. Go to Eris Morn's apartment in the Last City and step through the glowing green tear into her throne world.
2. Turn 90 degrees right and drop off the ledge into the hidden room; interact to load into the Unknown Antechamber.
3. Interact with the chess plates and shoot grid squares (A-H, 1-8) to place pieces (knight, rook, pawn, queen, bishop), with delete, take and undo options, to checkmate the black king.
4. DualShockers says you need the 60 hidden chess pieces collected first. This is the Episode: Heresy puzzle.

Unconfirmed

Sources describe a related triumph, En Passant (27 puzzles). Whether Checkmate matches the first puzzle or the whole set is unconfirmed; reward unknown.