Hollerith⁵ consists of a 6x6 game board with a hole in each space large enough to hold a marble, as well as marbles in two colors and five perforated plates; each plate covers a 3x3 area, which means that four of the plates together cover the entire game board. Each perforated plate has nine holes so that you can see whether a hole in the game board is filled with a marble, but only one or two holes per plate are large enough for a marble to pass through. (These holes are marked as such on the plates.)
On a turn, you push the fifth plate onto the game board, displacing one of the plates already there, then you insert one of your marbles into an unoccupied hollow of the game board. Players alternate turns until one of them forms a row of four marbles and wins. Note that if you cannot insert a marble into an empty space on the game board, you lose instantly.