lantern

Tap or click one of your pieces, then a dotted square (a dashed ring means a capture). You play the side shown under the board; the page plays the defender and always picks its most stubborn reply. These are short tactical positions, not full games. Standard chess rules apply, including check, castling, en passant and promotion.

Move limits count only your moves. “Mate in 2” means checkmate on your second move whatever the defender does. A ◆ and dashed border mark the target piece, and the marker follows it if it moves. Capture means taking that piece within the limit, even if it is recaptured afterwards. Win also guarantees at least the stated material gain after the defender’s best reply and recapture (pawn 1, knight/bishop 3, rook 5, queen 9).

Every move that still forces the mission is accepted. A legal move that lets the defender off the hook is shown as a miss and not played. Undo takes back your whole turn (your move and the reply), as often as you like; Reset restarts the puzzle. Hints go from the idea, to the piece, to the move.

Keyboard: Tab to the board, arrows to move around, Enter or Space to pick a piece and a square, Escape to deselect, U to undo and R to reset. Progress is saved on this device when storage is available. Everything works offline.

All ten positions come from the Lichess open puzzle database, released under CC0 1.0 Universal (legal text). Individual authors are not supplied, and no endorsement is implied. Each position is the source FEN after the source’s first (setup) move; missions, move limits, accepted alternatives and defender replies are re-derived by Lantern’s own exhaustive search, and the titles, hints and explanations were written for Lantern.

Rules use chess.js 0.10.3 by Jeff Hlywa, under the BSD 2-Clause license. The bundled copy exposes legal-move hooks for local verification. No remote engine or network request is used.

Copyright (c) 2020, Jeff Hlywa (jhlywa@gmail.com)
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