Board is a square board (19x19 i think) At each edge there are 3 "special edges". A tile is a 1x3 piece that has a "canal" in it. It is internally contigous and opens at 3 of the 8 possible ends.
In my variation, each player starts with 3 tiles, turns go in order, player draws a tile and places a tile. First tile placed must cover the center of the board. All additional tiles placed must connect all "open" edges to an "open" edge of a currently placed tile, the edge of the board or open space.
Points are calculated by canals touching side A * canals touching side B. Every spot a canal touches is one point, if the canal touches the afore mentioned "special edge" its worth 2 points instead.
On your turn, you *must* place a tile, the game ends when a player turn occurs in which they cannot play a tile in a valid spot. (In online game environment, I would state that a player who feels they cannot place a tile click on "cannot place tiles" option, which allows the other player to place any of that players tiles for them, if they cannot find a spot either they click on "agree" and the game ends.)
In the 3 player variation, one player bids, the bid is how many points they think they can keep the other players from getting, a bid of 17 is stating that neither of the 2 players working to connect canals can get 17 or more points. Bidding goes round until someone bids lower than anyone else is willing to bid, that person then is not playing to connect 2 sides with canals, they are playing to prevent either player from making enough connections to get to the bid amount.