Block strips dominoes to its tactical core: there is no boneyard to rescue you. If you cannot play, you pass, and everyone at the table learns something about what you are holding.
A standard double-six set has 28 tiles: every pairing of two numbers from blank to six, with no duplicates. A tile showing the same number twice, like 5|5, is a double.
The tiles nobody was dealt sit face down in a pile called the boneyard. In a four-player game dealt five tiles each, twenty tiles go out and eight stay in the boneyard.
The first double played becomes the spinner. It is laid crosswise, and once both ends of the main line have grown, the chain can also branch off its two sides - so the layout can have up to four open ends instead of two.
You never draw. The boneyard sits untouched for the whole round. Every pass is public information: if a player passes on an open end showing 3, everyone now knows they hold no threes. Good Block players count those passes and deliberately keep the board on numbers their opponents have shown they cannot answer.
When all four players pass in succession the round is blocked. The player with the fewest pips in hand wins it and scores the pips held by the others. A tie for the lowest count means nobody scores that round.
