- tall or short;
- red or blue (or a different pair of colors, e.g. light- or dark-stained wood);
- square or circular; and
- hollow-top or solid-top.
Players take turns choosing a piece which the other player must then place on the board. A player wins by placing a piece on the board which forms a horizontal, vertical, or diagonal row of four pieces, all of which have a common attribute (all short, all circular, etc.). A variant rule included in many editions gives a second way to win by placing four matching pieces in a 2×2 square. This is the best way to play.
Quarto is distinctive in that there is only one set of common pieces, rather than a set for one player and a different set for the other. It is therefore an impartial game.