PLUS ONEFrequently Asked Questions
What's actually different between ChessPlusOne and regular chess?
Just one thing structurally: the board has 9 ranks instead of 8, with the extra row inserted through the middle rather than tacked on at either end. Every piece moves exactly as it does in standard chess — the same captures, the same castling, the same en passant and promotion rules. Nothing was added, removed, or reskinned. The entire variant comes from a single change to the geometry of the board.
Why add a row instead of just playing normal chess?
Because that one extra row quietly breaks the thing competitive chess is most built around: memorized opening theory. In standard chess, the first several moves of a serious game are often recall, not calculation — centuries of analysis have mapped the opening book to a remarkable depth. Push the armies one row further apart and that book stops applying almost immediately. A "book" opening in ChessPlusOne is, at most, a couple of moves old before both players are genuinely thinking again. That's the whole design goal: keep everything that makes chess chess, and remove the part where preparation outweighs understanding.
Does the extra row change which pieces are strong?
It shifts the balance in small but real ways. Pieces that need open lines and time to develop — bishops, rooks, the queen — get a little more room to maneuver before contact, while the king's relative safety behind its own pawns lasts a touch longer since the opposing army is physically farther away at the start. Knights, with their fixed short hop, feel the extra distance the most: a knight that would be perfectly placed on move 4 of a standard game needs an extra tempo to get there here. None of this is extreme — it's still recognizably chess — but it's enough that transplanting a standard-chess opening move for move isn't a reliable plan.
Is ChessPlusOne free to play?
Yes, completely — no account, no paywall, no limited "free trial" of anything. The site carries a small amount of advertising to help cover hosting, and there's an optional Ko-fi tip jar for anyone who wants to support the project directly, but every mode, every AI level, and online multiplayer are fully open to everyone.
Can I play without an internet connection?
Yes. Once you've loaded the site once, it can be installed like a native app (see How to Play for the steps on Android and iPhone), and from then on, Two Players and Player vs AI both work with no connection at all. Only the parts that are inherently shared with other people — online multiplayer, the live player-count bar, and the world map of games being spectated — need you to be online.
How strong is the strongest AI level, realistically?
Level 9, "Ctrl+Alt+Defeat," searches as deep into the position as it can within a 30-second-per-move budget, using the same kind of techniques (alpha-beta pruning, a transposition table, a quiescence search to avoid being fooled by a move that looks safe one ply too early) that real chess engines rely on. It is deliberately built to be a genuine fight for a strong club player, not a token "hard mode." If level 9 feels like too much, the status bar shows each level's expected response time before you start, so you can pick a level that matches both the challenge and the patience you've got for that session.
Is there a rating or ranking system?
Not yet. Right now the focus has been on getting the core game, the AI, and online play solid. A rating system is a natural next step once there's a large enough base of games to make one meaningful, but it isn't built today — see About and Updates for what's actively in progress.
Can I play with a friend who isn't in the same room?
Yes — choose Multiplayer under Online multiplayer in the side panel, create a room, and send your friend the short code it gives you. They enter it under Join Room and you're connected directly to each other, no account needed on either side. If someone's connection drops mid-game, the room stays open and they can rejoin with the same code and pick up exactly where the game left off, as long as the player who created the room keeps their tab open.
What happens if I lose or close my tab mid-game?
Locally or against the AI, nothing is saved automatically — use Save Game beforehand if you want to come back to a specific position later. Online, the game itself survives a dropped connection (see above); what doesn't survive is the room itself if the host closes their tab for good, since there's nothing left for the other player to reconnect to.
What's planned next?
The largest thing in progress is ChessPlusOne Telepathy, a 2-vs-2 team mode where two teammates share one army, move in a fixed order, and have no way to talk to each other during the game — coordination has to come entirely from reading the moves on the board. See Updates for a running log of what's shipped so far, including recent changes to the AI's strength and the status bar.