Sebastopol is a member of the Cyprus family played with a double six set.
The game uses a double six domino set and four players. There is also a three handed version of the game discussed in the Comments & Strategy section.
Each player gets seven tiles for his hand.
The player holding the [6-6] begins the hand by setting it in the center of the table. After he has played, the next player going clockwise around the table must place another tile in the sixes suit on the [6-6]. Each of the following players is so obligated until there are four tiles around the [6-6], making it a spinner from which the four arms of the layout grow. A player not able to play a tile in the sixes suit before all four arms have been started must pass his turn and play goes to the next player.
Once all four arms of the spinner are started, each player can add a tile to the end of any of the arms in the usual manner. Other doubles are played across the line but do not cause the layout to branch.
When one player dominoes, he receives the total of the pips on the tile in the other player's hands as his score.
If the games blocks, then the player with the lowest total is the winner. He scores the totals from the other players and then subtracts his own score from that total. If there is a tie for lowest score in a blocked game no one scores.
The game is played for 60 points, or more points by agreement.
Notice that there are seven tiles in the sixes suit. This means that five of them will be in the center of the table when the opening spinner is completed. When one of the remaining tiles in the sixes suit is played, it will block that arm of the spinner to all but the other sixes tile.
The opening spinner will have almost all the other suits (zero to six) on the arms of the spinner, so you can watch the other players to see what arms they do not play on to determine what suits they do not have in their hands.
Alexey Lobashev describes a variation played in the Ural region of Russia. The first deal is started by the player with the [6-6], the next by the [5-5], then [4-4] and so on down to [0-0], then back to [6-6] and around again if necessary. It is not necessary to play on all four sides of the starting double before extending the arms - players have a free choice where to play. Some play that a double added to an arm can be played face down to block it. No further tiles can be played on this arm, and if all four arms are blocked this way the game ends and is scored as a blocked game. Scoring is as above except that the [6-6] alone in a player's hand at the end counts as 66 pips and the [0-0] alone counts as 100. If the [6-6] or [0-0] are with other tiles, they count as 12 and 0 respectively. The winner is the first player to have a cumulative score of 101 points or more.
Another Russian variation, known as "osel" (goat), can be found at meingames.de. According to the rules on this site, it is possible to play several doubles at the same time if they fit on different arms of the layout. The game is started by the lowest scoring double that is dealt - the [1-1] is some player has it, if not the [2-2], the [3-3], etc.
The above game can be played by three players, still drawing 7 tiles each. A player unable (or unwilling) to play a tile must draw tiles from the boneyard until he can play or the boneyard is exhausted. If no one holds the required starting double, the game is started by the next double in sequence which is held by a player.
Fredrick Berndt (THE DOMINO BOOK; Bantam Books; ISBN 0-84-07601-4; 1975) gives a different three handed version of the game. Each player gets a hand of nine tiles, which leaves one left in the boneyard. The player with the [6-6] sets it to begin the hand and then draws the single tile from the boneyard to bring his hand back to nine tiles. Play then moves clockwise around the table.
If no player has the [6-6], then it is in the boneyard. In this case, the [6-6] is turned over to begin the hand and play starts with the same player who began the last hand. If this occurs on the first hand of the game, then players have to determine who will start in whatever way they wish.
A Russian version of Sebastobol known as Goat (Kozel) can be played online at meingames.de.