Of course it’s forbidden. That is a code

Maybe true as far as the first hand of the game but for 99.9999% of hands, if you come out with a double you better another one of that number to back it up. You can play any domino to start a hand, doesn’t have to be a double 6 (unless it’s the first hand of a game). You should always play towards your strength if you’re the opener.

Player with the five-blank had three options: 1. He had the last five which was a five-blank but coincidentally the other side was a blank (blank-one). With him having the last five and it was a five-blank, if he played on the blank side where both ends are fives, the game would blocked as there are no more five's on the table. In that case, the pieces would be added and team with lower count wins. BUT player with the five-blank had a sure win anyways. 2. He could've played the blank-three instead, let other players throw their playable pieces, and then win with the five-blank. The difference here with both options, is that more points are collected by blocking game. 3. Player with five-blank could've played piece on the double five instead, which would leave both ends with a blank. This wouldn't be a smart move as option two is way more strategic and a sure win. There's a chance he can still win with this play, but the outcome depends on what the other players play.

@@pedrito287 thank you men .. i appreciate it