In Metro Domino, you use domino tiles to build metro lines across the city.
Each player starts with nine dominoes from a 9x9 set, and one random domino is placed in the central starting station. On a turn, you can draw a domino from the boneyard (i.e., the supply of dominoes) or place a domino at the end of an active line as long as you can match the number at the end of the line; the starting station can have two lines built off of the starting domino. If you place a double domino, take another turn immediately.
The starting station indicates that five dominoes must be placed in a line before a new station is opened. If you place the fifth domino in a line, draw a random station from the deck, then place it at the end of the line and mark it with one of your tokens. Each station has two lines off of it, with a starting domino half on each line and a length the line must reach before a new station is built on that line.
Players continue to take turns until either one player has emptied their hand of dominoes or the fifth station has been put into play. At the time, players score, earning 1 point for each station they started and losing 1 point for each domino still in hand.
Each city edition of Metro Domino appears to have identical gameplay, but with differing station lengths and values.