One of your two allies is secretly working for Black.
How to play
You and two bot allies share the White army and take turns in rotation: you command files a–c, Ally Ash files d–e (with the king), Ally Rook files f–h. One of the two allies is secretly playing for Black — mostly it plays plausible moves, but it sneaks in sabotage. Study the log, then use Accuse once: if you are right, the traitor is expelled and you take command of its pieces; if you are wrong, Black immediately gets a free extra move. Black is a team of three bots too, taking turns with files a–c, d–e and f–h. When a side is in check, any of its pieces may answer the check. Checkmate Black to win. Pawns auto-promote to queens.