LABS CHESS v10.11 • FULL TECHNICAL BREAKDOWN

AI ENGINE
• Alpha-beta minimax, side-to-move derived from the position (no colour inversion)
• Iterative deepening — depth 1, 2, 3… until the time budget runs out
• Quiescence search on captures & promotions (no horizon blunders)
• MVV-LVA move ordering, so alpha-beta actually prunes
• Mate scores are depth-adjusted: it finds mate and prefers the fastest one
• Eval: material + piece-square tables + pawn structure + bishop pair + endgame king activity

WHAT MAKES THE 12 LEGENDS DIFFERENT
• Depth — how far ahead they look (3 or 4 plies + quiescence)
• Aggression 1–12 — weight on king-attack tropism and checks. High aggression will give up a pawn to pile pieces onto your king; low aggression plays it quiet
• Noise — centipawn jitter at the root. High noise = plays the 2nd/3rd best move often = beatable. LETHAL has zero noise

TIMERS (White vs Orange)
• White timer runs on your turn, Orange on the computer's turn
• Count-up clocks, no duplicate intervals, format MM:SS

THINKING TIME
• The budget is a real search deadline, not a sleep — the search aborts when time is up, and the bot moves as soon as it has finished its deepest allowed pass
• Base: depth × 750ms + 1.8s • Magnus: 5s at up to depth 6 • Koblence: randomised 3.5–8.5s
• Thinking 10s / 6s hard-cap the budget for every bot

FEATURES
• 10 piece themes (5 glowing + 5 flat) • flip board • undo (full move) • hold "Last move"
• Recommend move (neutral depth-3 search) • under-promotion picker • board coordinates
• Keyboard playable (Tab + Enter) • preferences saved to localStorage

CURRENT OPPONENT
THE BOARD
• Squares are 1.85:1 apart in the dark edition and 1.88:1 on paper. They used to be 1.19 and 1.29 — a checkerboard you could not see, and the pattern is what you read diagonals off
• Every piece is two layers of one font: the solid glyph is its body, the hollow glyph of the same piece is its contour. So a fill never has to carry a piece — a white fill on a light square is 1.03:1 and can't — and every side of every theme clears 3.5:1 on both squares
• Highlights are on four separate layers (tint, dot/ring, box-shadow, background), so any combination of selected + capture + last move can be true at once. No !important left

HOW TO USE THIS BOARD

PLAYING
• Click a piece, then its square. Legal squares show a dot; a capture shows a ring.
• Four ways to play — VS COMPUTER (twelve opponents, each with a real playing character), PASS & PLAY (two people, one screen), LIVE MATCH (two devices over the wire), and DAILY MATE (one verified mate-in-N, new every day, with a streak).
• Time controls sit in the Game group: ∞ is a stopwatch that only records, 1m is Bullet, 3m and 5m are Blitz, 10m is Rapid. Pick one before the first move and the clocks count down; pick one mid-game and it applies to the next game.
• UNDO takes back a whole move — your move and the computer's reply — because taking back only half would leave you staring at a position you never chose.

PLAYING SOMEONE ELSE
• LIVE MATCH → CREATE INVITE gives you a link and a seven-character code. Send either. Whoever opens it takes Black; you keep White.
• The link copies itself when you create it, and the tab title says “Your move” when it is.
• Come back any time. Reloading, closing the tab or losing signal does not lose your seat — open the same link and you are sat back down.
• VISITOR LINK hands out a spectator address. Anyone with it watches the game move by move and cannot touch it; their controls are switched off and their page says so.

WHEN THE GAME ENDS
• WATCH THE REPLAY steps through the whole game — first, back, play, forward, last — at 1×, 2×, 4× or half speed, with a line under each move saying what happened: what took what, what was check, where it turned.
• SHARE THE GAME gives you a link that replays it for whoever opens it, an email with the same, or a .pgn file any chess program can read — with every move's plain-English reading carried in the comments.
• UNDO LAST MOVE is offered against the computer, so a game lost to one slip is not over.

READING THE BOARD
• The bar above the board is the engine's read of the position — White's share of it — and the number beside it is in pawns. +1.0 means White is a pawn up in effect.
• Ratings name each move after it: Book, Brilliant, Great, Best, Good, Inaccuracy, Mistake, Blunder. Turn them off in the Board group if you would rather not know.
• RECOMMEND asks the engine what it would play, THREAT shows what your opponent is threatening, and AUTO MOVE plays a neutral move for you. All three are computer-mode only, and the whole group greys out between humans.
• Click any move in the record to see the board as it was; BACK TO LIVE returns you.

MAKING IT YOURS
• Ten square themes and ten piece themes, stored per edition — a choice made on paper cannot wash out the dark board.
• 2× doubles the board on a desk; it is on by default there, and the pill turns it off for good if you would rather it were not.
• FLIP turns the board round. PGN, FEN and POSITION in Share copy the game, the position, and a link that opens the board exactly as it stands.
• Nothing here needs an account, and an unfinished game against the computer is waiting where you left it when you come back.