Othello
Othello, the disc-flipping game also known as Reversi, on an eight-by-eight board in the browser. It plays on a phone or tablet as well as a computer. Pass the device across the table, play against the computer at one of three levels, or send a friend a link and play on two screens.
How to play
Black moves first. Place a disc so that it traps a line of your opponent's discs between it and one of yours, across, down or diagonally, and every disc in that line turns your color.
A move has to flip something, so the board only lets you tap squares that do. They are marked with a dashed hint, and the last move wears a gold ring.
If you have no legal move, your turn passes on its own and the game says so. The game ends when neither side can move, usually on a full board, and whoever has the most discs takes it.
Playing against the computer
There are three opponents, named for how they play. SLOPPY plays any legal move. GREEDY takes whichever square looks best right now, corners loved and the squares beside them feared, with no lookahead.
GREEDY is the lesson: Othello punishes the player who grabs discs in the middle game, because those are the discs that flip back.
PATIENT thinks four moves ahead, weighing position and how many moves each side will have. Once ten or fewer squares are empty, it stops estimating and solves the rest of the game exactly. You open as Black, and colors swap on the rematch.
Two player, by link
PLAY WITH A LINK opens a board and gives you a link to send. Whoever opens it takes the other color, and anyone who arrives after that watches. There are no accounts: you type a name, and a reload puts you back in your own seat.
Opening a board takes a password Matt hands out in person. Joining from a link needs nothing.
There is no server deciding the game, because Othello hides nothing. Both browsers run the same rules and check every move the other sends. Colors swap for each rematch.
Records
This browser keeps count of the games you have played, a won-lost-drawn record for games by link, and a separate record against each computer opponent. The record you are chasing sits above the play button.
PASS & PLAY is the big button on the menu: two people, one screen, taking turns. It needs no link, no password and no second device.