"Dag en Nacht" is Dutch for "Day and Night."
The board is an nxn squared board, where n is an odd number between 11 and 19. A 15x15 board is considered average. The board is laid out in a checkered pattern of black and white spaces. The white spaces are the most numerous, with the four corners all being white. The board starts off empty.
The players are Black and White, with Black going first. Each has a supply of stones in her color that fit the board spaces.
On a turn, a player takes one of the following two actions:
Drop a stone of her color onto a black space — a stone may never be entered in a white space.
Shift a stone of her color already on the board a single space orthogonally — in other words, move a stone from a black space into a neighboring white space.
The winner is the first player to get five of her stones in a row horizontally or vertically, or four stones in row diagonally on white spaces. Stones on black spaces cannot win with a diagonal line.
Optional rule: Players may decide to help mitigate Black's first move advantage by adopting a rule prohibiting Black from winning with the easier B-W-B-W-B orthogonal line and only allowing Black to win with the harder W-B-W-B-W orthogonal line.