Whole games, every move a trial

Your book plays itself to where it ends, then you play the game out to the finish against a guarded 2100 (it never hangs a piece to one move). Every move is judged against the master bar the moment you play it: a master move plays on, a weaker one stops with the reason. A move that costs a pawn or more is taken back and the best move plays on, so you are never stuck in a lost game. Opening misses go to Opening Flow's spacing; later misses come back once as a warm-up before your next game.