21

Upon reaching the North Pole pub, the group notices the chessboard, but the mysterious elf is nowhere to be seen. You approach the bartender and ask about the elf you played that mirrored games against. He shrugs, "Haven't seen anyone like that here. I only saw you playing Wesley."

David Snowell looks towards the back room. "Perhaps we should check there? If there's an elf nobody knows about here, he might be hiding," he suggests. Before anyone can move, Wesley Snow quickly interrupts, "No need! It's just old pub storage."

As you ponder Wesley's response, Magnus Carolsen suddenly notices a large mirror near the chessboard. "Was this always here?" he asks. You look into the mirror, seeing the reflection, and it dawns on you, "I wasn't playing against an elf," you whisper. "I was playing against mys...elf."

The realization sends a shiver down your spine. You take a seat at the chessboard, facing the mirror. "I'm going to play again.", you say. "I will conquer my reflection, once and for all, and this time with my bishop!"

The same rules as on Day 4 apply. The only difference is that you will mate with a bishop on move 7, instead of with a rook on move 6.

Given the situation where your opponent is committed to mirroring your every move, can you, as White, find a way to give checkmate with your bishop (an original bishop, not a promoted one) on move 7? White makes 7 moves, Black makes 6. You can't make moves that aren't possible to mirror. For example, after 1. e4 e5 2. Qh5 Qh4, you wouldn't play Qxh4, since that would be impossible to mirror. Here's an analysis board.

As usual, ask in our Discord if anything is unclear.