You take turns placing stones on the squares of the board. You may only play a stone that captures some of the other player's stones. A stone is captured if there is one or more opponent's stone between your new play and another stone of yours. The captured stones flip over to show the opposite color. For example:
In this example, is it black's turn. The square on the left is a valid move, and is marked with a small gray dot. The square on the right is not a valid move, because it doesn't border any white stones and would not capture anything. If black plays on the left, the three white stones on the left would be captured and become black. The white stone in the middle would not be captured, because the capture stops at the first black stone.
If you cannot capture any of the other player's stones, you must pass. The app will determine this for you and give control back to the other player after showing this on your part of the score board:
When the board is full, the game is over. The player with the most stones wins. The app will show this on the score board for the winner:
You can start the game over at any time using the "Reset Game" button at the bottom.
To play locally, two players take turns clicking or tapping on the same device to make their moves. This works really well with a tablet or phone laying on the table between two players, but can also be done on a laptop or desktop with a mouse.
To play offline, just load the URL. If you've loaded it before, it should be cached and available offline. On some platforms, such as Android, you may also be prompted to install the app to your home screen.
To play over the internet, click or tap on the "P2P Multi-player" button at the bottom of the screen. A video chat will appear under or to the right of the game board. Click or tap on the text under "Your ID" to copy it to the clipboard. Send this text to a friend. Your friend then pastes your ID into the field labelled "Your friend's ID" and hits enter on the keyboard or tablet/phone's on-screen keyboard. This will start the connection between you and your friend.
During the game, you can see and talk to your friend while you play. There is a mute button which can be used to mute or unmute the connection. You can use the "X" button on the video chat to end the connection.
When it's your turn, your color will have a halo behind it at the top of the scoreboard, and all valid moves will be marked for you with a gray dot. Either player can use the "Reset Game" button at the bottom of the board at any time to start a new game.
This game is meant to be social and played with friends and family. It is not meant as a way to meet internet trolls, so there is no match-making service. You'll have to send your randomly-generated ID to others using some other system, like a text message, chat, or email.
This probably won't work on IE. It should work on any current browser. If it doesn't work for you, please file a new issue here: https://github.com/joeyparrish/othello/issues