🔮 The Oracle
How to play
Tap a piece, then the square to move it to. Yellow dots show where it can go. Castling: tap the king, then the square two over. When a pawn reaches the far row you choose what it becomes. The last move is ringed on the board and a king in check glows red.
Before your first move you can choose your colour, how many moves ahead the opponent thinks (1 to 6 — higher is stronger; 5 and 6 can take a long time per move, especially on a phone), and a time control. These lock once play starts.
Take back undoes your last move and the reply. Offer draw is accepted when the opponent isn't ahead. Resign ends the game. Copy PGN copies the whole game in the standard format that any chess app can open. Your game is saved automatically in this browser, so you can come back and resume it.
Draws: stalemate, the same position three times, fifty moves without a capture or pawn move, or neither side having enough material to mate.
The Oracle
The Oracle is your optional advisor. Tap 🔮 to open it and it stays on duty at the start of each of your turns until you close it.
It uses minimax: for every move you could make it imagines each reply, each answer to that reply, and so on, assuming both sides play their best, then scores the move by how that ends. It looks as many moves ahead as the look-ahead setting, within about six seconds.
A green tag means the move forces mate; red means it gets mated against best play; amber is its judgement of the position in pawns (bigger is better for you). It weighs material, where pieces stand, room to move, king safety and pawn structure. The best move is highlighted on the board — purple piece, gold square, red glow on anything captured. Tap another line to see it instead. The Oracle only advises you; the opponent plays its own way regardless.