Everything that isn’t a rule of the game itself.
Yes. The full game — every rule, the tutorial, local two-player, online 1v1 matchmaking, the standard bot roster, and the daily puzzle — is free to play in your browser, no download or install. Ads and the optional Premium tier keep the servers on.
It helps, but it isn’t required. If you know how the six classical pieces move, the interactive tutorial teaches everything else: it plays a full guided game against you, introducing superposition, zaps, heals, captures, castling, and promotion one move at a time. You can replay it any time from the rules menu.
Yes. The game runs in any modern mobile or desktop browser, with a touch layout for small screens. There is no app to install.
No. Despite the quantum theming, every rule is fully deterministic — zap targets, collapse results, heal spillovers, and the conservation solver always resolve the same way from the same position. Nothing is decided by dice you can’t see.
Every day there is one puzzle, the same for everyone, mined from a real game at the moment one precise move mattered most. You are shown the position and asked to find the best move. Your answer is graded against the engine’s own ranked list of every legal move in the position.
Grades run from a star (you found the engine’s top move) through green, yellow, orange, and red, down to a skull. The grade reflects both how your move ranked among all legal moves and how much evaluation it gave away — a move that keeps a winning position winning still scores well even when it isn’t the single best choice, while a move that throws the position away earns the skull no matter how natural it looked.
Solving the daily puzzle records your result for that calendar day and feeds your streak — consecutive days played. After you finish, you get a spoiler-free, emoji-grade share card (in the spirit of Wordle results) you can paste anywhere. Skipping a day breaks the streak; watching the solution without playing records nothing.
You can play the tutorial, daily puzzle, local games, and AI games anonymously. A free account is required for Ranked online matchmaking and adds a profile rating, keeps your recent game history (up to 10 saved games on the free tier), unlocks new bot opponents after wins, and syncs your daily-puzzle streak.
Your profile rating changes after games against rated bots and after Ranked online games. Bot results use an Elo-style calculation based on the result and the bot’s rating; Ranked online results are calculated authoritatively by the server for both players. Ranked matchmaking begins near your current rating and gradually widens its search while you wait. Local, Unranked online, and signed-out games do not change rating.
Yes. Every signed-in player can step through a saved game move by move, branch from any position to explore a different continuation, and create a public replay link to send to someone else. Replay mode has no engine evaluations or suggested lines; those analysis tools remain part of Premium game review. Free accounts retain their latest 10 games, while Premium accounts retain up to 1,000.
Premium is $3/month and exists because Quantum Chess is built and run by one person. It removes ads and adds game review with engine moves, up to 1,000 saved games, access to all eighteen active bots (including six Premium-only opponents), and the full character-avatar roster with 32 more taglines and sayings. Subscriptions are handled by Stripe and can be cancelled any time from your account.
Not a subscription person? A one-time $5 tip buys three months with no ads, five engine game reviews per day, and access to the six Supporter bots. Tips stack — tip twice and you have six months.
After any finished game, the review board replays it move by move with an evaluation graph, marking the moments the game swung and showing the engine’s preferred move where yours went astray. Free accounts can unlock three reviews per day by watching a rewarded ad for each one, tippers receive five per day without ads, and Premium includes unlimited reviews. It is the fastest way to find out where your King count quietly collapsed.
Every bot is a fictional parody mashup of a deceased scientist and a deceased chess legend. Their portraits, personalities, sayings, and ratings are invented; none depicts a real person, and no affiliation or endorsement is implied.
Feedback, bug reports, and hellos all go to contact@quantumchess.ninja. Bug reports with the move list attached (copyable from the in-game history panel) get fixed fastest.
The complete rulebook covers every rule on one page, the strategy guide covers what to do with them, and the learning library explores individual ideas in depth. In the game itself, the tutorial and the paginated rulebook live behind the book icon in the side menu.