Day 14 - Retrograde

Santa sits in the lab’s central chair, his expression a mixture of concern and curiosity as David explains the anomalies. After a moment, Santa leans back, stroking his beard. “An anomaly serious enough to wake me early. Tell me the full story.”

Magnus chimes in. “It’s not just the cryo-chamber. We’re dealing with interference from the singularity, affecting time and space throughout the factory.”

You, still piecing the situation together, ask Santa, “Why do you need to be frozen every year anyway?”

David glances at you, his expression thoughtful. “It’s time you knew how the operation works,” he begins. “We’ve engineered an environment around the sleigh that isolates him and his reindeer from the rest of the universe. The system manipulates spacetime itself.”

Magnus adds, “The field compresses the space ahead of the sleigh and stretches it behind. This creates a localized spacetime bubble where everything inside moves independently from the outside world.”

David nods. “Inside this bubble, the sleigh can reach speeds close to the speed of light. As it accelerates, time dilation kicks in. For Santa, time slows dramatically – what feels like a full year inside the bubble passes as only a single night outside.”

Santa nods, then gestures to the chessboard nearby. “Speaking of time… How did this position occur?”

Given that this position could be reached in a legal game of chess, what was the last move played? You only need to provide the last move for the last player who moved, not for both. You need to also provide the square the piece moved from. If a piece was captured, you need to also provide the piece captured.

For example: If a Queen on b2 moved to a3, you write Qb2-a3. If a Queen on b2 captured a Rook on a3, you write Qb2xRa3 (Qxa3 is not enough).