CHESS PLUS ONE

How to Play

CHESS PLUS ONE is classic chess — same pieces, same moves, same objective — played on an unusual board: 8 columns and 9 rows, with an extra row inserted through the center of a normal chessboard.

The board

Files (columns) are labeled a through h, same as standard chess. Ranks (rows) run 1 to 9 instead of 1 to 8 — the extra row sits in the middle of the board, giving every piece a little more room to maneuver before the armies meet.

The rules

Nothing about how the pieces move has changed. Pawns, knights, bishops, rooks, queens, and kings all behave exactly as they do in classic chess, including castling, en passant, and pawn promotion. The objective is the same too: checkmate the opponent's king.

Making a move

Click a piece to see its legal moves highlighted on the board, then click one of the highlighted squares to move there.

The Turn Bar

The bar just above the board shows whose turn it is — the White or Black side lights up depending on who's to move. If the side to move is in check, the center of the bar turns red and reads CHECK; if it's checkmate, it reads CHECKMATE instead.

White and Black are also buttons: tap either one to draw a soft pink line on the board, from the square that color's most recent move started on to the square it landed on. Only the latest move per side is ever remembered — the moment that color moves again, the line updates to match. Tap the same side again to hide it, or the other side to see its move instead.

The Avatar

The little face in the side panel reacts to how the game is going. It thinks quietly while it's your move, dozes off if nobody moves for a long while, and lights up for the moments that matter: a big smile for a strong capture, a wince if a move hangs material for nothing, wide eyes for check, and a bigger reaction still for checkmate. If you've set a Binary Timer (see below), it also gets visibly excited the moment the very first move of a timed game is made — the clock is running now.

Game modes

• Two players (local) — play against a friend on the same device, taking turns.
• Player vs AI — choose your color (White, Black, or Random) and an AI difficulty level from 1 to 9 (see below).
• AI vs AI — watch two AI opponents play each other. Choose a difficulty, then press PLAY to begin — the game waits for you rather than starting on its own. Pause and resume anytime, or Reset for a fresh match.

Difficulty levels

Nine levels, from a coin flip to the strongest the engine can manage:

1. Coin Flip — picks a legal move at random.
2. Rogue Pigeon — grabs whatever looks tastiest, no real plan.
3. Park Hustler — a genuine, if modest, search.
4. Blitz Addict
5. Basement GM
6. Chess Nerd
7. Endgame Sage
8. Silicon Overlord
9. Ctrl+Alt+Defeat — the maximum, for a genuinely serious challenge.

From level 3 up, the AI searches as deep as it can within a short thinking budget that grows with the level — level 9 can take up to 25 real seconds on a single move. If you've set a Binary Timer, a level that could realistically think longer than the clock can spare has its fastest, incompatible timer options grayed out (and vice versa — picking a fast timer grays out the levels that wouldn't be fair to it). This keeps a strong AI from ever running itself out of time by thinking too long.

The Binary Timer

Set Binary Timer, in the side panel, adds a real chess clock to the game — shown not as ordinary digits, but as two rows of small dots (one above the board, one below), each split into three sections for hours · minutes · seconds, left to right.

How to read it: every dot has a number printed just above it (8, 4, 2, 1 for the hours section; 32, 16, 8, 4, 2, 1 for minutes and seconds). A dot lit up in gold counts; a dark dot doesn't. Add up the numbers above every lit dot in a section to get that section's value — for example, if 16 and 1 are lit in the minutes section, that's 17 minutes left. It's the same idea as a binary wristwatch.

Pick a starting time with the buttons — Off, 3, 3-10, 10-25, or 60+ (a representative time from each range: 3, 5, 15, and 60 minutes per side) — and the clock starts immediately for whoever moves first. Each player's own clock only runs during their own turn, and switches the instant they move; run out of time and that side loses the game on the spot, no matter the position on the board.

The timer works in Two players (local) and Player vs AI — in Player vs AI, the AI is on the same clock as any other opponent would be, ticking down on its own turn just like yours does. It's turned off entirely in AI vs AI, since nobody's actually racing a clock there.

Picking a time control only ever sets it up — the clock doesn't start ticking, and no move can be made, until you actually press PLAY. If a few seconds go by without that click, the Avatar will remind you and the PLAY button starts pulsing gently. Once the game is under way, the timer locks — no switching to a different time control or turning it off mid-game — until the game ends or you press Reset. And each player's clock lights turn red once a third of the starting time is left (a minute left of a 3-minute game, five minutes left of a 15-minute one, and so on) — a visual warning that time is running short.

Game Time

Just below Set Binary Timer, Game Time shows how long the current game has been going — the same binary dots, but counting up and with only hours and minutes (no seconds). It's not a limit of any kind, just a stopwatch for the game, and it works in every mode, with or without a Binary Timer.

It begins when the game does: when you press PLAY (AI vs AI, or any timed game), or with the first move if the game has no PLAY step. Pause in AI vs AI pauses it too, and PLAY picks it up again. It stops for good the moment the game ends — checkmate, a resignation, a draw, or a flag falling — and goes back to zero when you press Reset. Online, each player's own screen keeps its own Game Time, so if someone reconnects theirs starts counting again from zero.

Ending a game: Resign and Reset

Resign concedes the game right away — the other side wins, whatever the position on the board. It's available in Two players and Player vs AI (there's no one to concede for in AI vs AI, so it's hidden there). Against the AI or online it's always you giving up; playing locally with a friend, it resigns whoever currently has the move, since you're sharing one screen.

Reset just starts over — no winner, no loser. That's fine early on, but not once a game has genuinely gotten underway: after 5 minutes of play with no clock, or half the starting time on a timed game, Reset turns itself off and Resign starts pulsing gently instead — the proper way to walk away from a game that far along.

Draws

Offer Draw asks your opponent (the AI) if they'll agree to a draw. Claim Draw becomes available once the rules genuinely allow it — after threefold repetition of a position, or under the 50-move rule — and ends the game immediately when used.

The move-history "time machine"

Once a game ends, click any move number in the move-history bars above or below the board to see exactly what the position looked like at that point. Click the result (or the same move again) to jump back to the final position.

Save & load a game

Save Game downloads the game so far as a small file to your own device — every move played, the mode, and the result if it's already finished. Keep it as long as you like; we never see or store it. Load Game reads one of these files back in and replays it move by move, so you can review a game later, even offline, or send the file to someone else to load themselves.

Online multiplayer

Use Create Room to host a game and get a room code, or Join Room to enter a code a friend shared with you. One of you plays White, the other Black. A newly created room waits three minutes for someone to join; if nobody does, it closes on its own.

If either side's connection drops, the game isn't lost — as long as whoever created the room keeps their tab open, the other player can rejoin with that same code and pick up exactly where things left off. Undo isn't available once you're playing online, since it would have to undo the same move for both players at once.

Reset needs your opponent's agreement. Online, pressing Reset doesn't restart anything by itself — it sends your opponent a request, and the game only resets if they press Accept. If they decline, or don't answer within 30 seconds, the game simply carries on (after a declined request you'll need to wait a moment before asking again). While a request is waiting, the board is locked for both of you. That way nobody can wipe a game they're losing just by hitting Reset. Playing locally or against the AI, Reset still works instantly, since there's no one to ask.

Turn chime

Playing Player vs AI or an online multiplayer game, a soft bell plays the moment it becomes your move while you're away on another browser tab or window — a gentle way to know you're up without having to keep checking back. It stays quiet whenever this tab is the one you're already looking at, and it never plays in local Two players or AI vs AI, since neither of those has a single person waiting on a turn. Turn it off any time with the switch in the side panel.

Installing the game

On a phone or computer, Chess Plus One can be installed like an app: on Android, Chrome offers "Add to Home Screen" (or an install icon in the address bar); on iPhone, use Safari's Share button and "Add to Home Screen." It opens full-screen with its own icon, no browser bar, and Two players / Player vs AI keep working with no internet connection at all — only online multiplayer, the Stats Bar, and the live map need a connection.

The Stats Bar

The bar under the title, as wide as the board and side panel together, shows how many people are playing right now and how many games have been played in total, split by mode. Its little light is green only while one or more people are playing — with nobody playing (or if the numbers can't be loaded) it stays off.

Watching a game live

The world map near the bottom of the page shows, roughly, where people are playing right now. A dot that lights up gold and pulses belongs to a game you can actually watch — click it to join as a spectator. (Use the +, −, and Reset buttons, your scroll wheel, or drag the map to zoom and pan around first if you need to.)

Watching is read-only: you see every move as it happens, but you can never move a piece, offer or claim a draw, reset, or undo — there or on any other game. Use Stop Watching whenever you're done.

The Spectator Bar

Below the board, this bar shows a flag for whichever country each side is playing from (once it's known) — or "AI" for a computer-controlled side — with how many people are currently watching that game shown in the middle. See the Privacy Policy & Cookies page for how that country is determined and shared.