Overview
Matador (Spanish, "killer" or "bullfighter") or Matadore, sometimes called Russian Dominoes, is a domino game for two to four players using a double six set of dominoes. It is one of the blocking family of domino games in which the object of the game is to be the first to go out, while blocking one's opponents from doing so. Its distinguishing feature is the unusual rule of playing tiles so as to combine pips instead of matching numbers.
Number of dominoes
After it is decided who goes first, usually the player who picks the highest double (a domino with both ends showing the same number of spots), each player gets five tiles, with the leftover ones set aside in an area known as the boneyard.
Connections
During play, players must connect either end of the line of tiles not with a matching number on either end, but one causing the two connecting ends to have a total of seven pips, i. e. a six-spot end must be connected with a one-spot one, a four-spot with a three-spot, and a two-spot with a five-spot. Doubles are placed endwise and count the same as single dominoes. Blanks are closed to play of any domino other than a "matador." A "matador" can be either the double-blank domino or one containing a total of seven pips (4-3, 5-2, and 6-1). A player can also place a "matador" at any time without any regard to the numbers at either end of the domino line.
From Wikipedia (CC BY-SA 4.0).