About Chess
Chess on the Warden's war-table, by the full rules: castling, en passant, promotion to any piece, and the draws a table declares on its own — stalemate, threefold repetition, the fifty-move rule and bare kings.
Ten keepers sit across from you, from Page, who is still learning the moves, to Oracle, the strongest this table holds. They are one engine at ten strengths, set by how far it may search rather than how long, and every step up the ladder was measured in a tournament of eighty games so that no keeper is a wall after the one before it. Each keeper keeps your fewest moves to a win and your fastest win; a game in which you took a move back does not count for either.
The Trials are 200 mates in one to five from the Lichess puzzle database, each re-proved from scratch here — exactly one first move keeps the mate in time, and it cannot be done faster — and 20 king-and-queen and king-and-rook endgames judged by an exact table built in your browser. The table accepts every move that still mates in time, not just the book line, and the defence always holds out as long as it can. A move that lets the king escape is taken back and the clock keeps running.
Every Trial keeps a public fastest time, and only your first solve counts; after that it is practice.
How to play
- Tap a piece, then one of the marked squares. A pawn reaching the far rank asks what it becomes.
- Keepers: choose one and a colour, then Play. Undo takes back your move and the keeper's answer, but the game then no longer counts for your best. Leave keeps the game for later.
- Trials: find the forced mate in the moves given. The clock starts when the position appears and does not stop, even if you leave.
- Endgames: mate the lone king within the count. A move that is still winning but too slow is refused, with the count it would have needed.
- Two players: both sides on one device, with the board turning each move if you want it to.
Controls
| Click · Tap | Choose a piece, then a square |
|---|---|
| ↑ ↓ ← → | Move between squares |
| Enter · Space | Lift or place a piece |
| U | Take back a move |
| F | Turn the board |
| Escape | Put a piece down, or leave the table |
All 220 Trials are re-proved by the release build's independent check; the keepers' ladder is measured and committed. The game in hand, your solves and keeper bests stay in this browser under morass.chess.v1; the fastest time on each Trial is public. No ads or analytics run inside the game.
