In Dr. Gomb (a.k.a., Dr. Button), everyone collects buttons. Players can collect any number from 1-5, but only one card's color can be different from the others. This card is called the "odd one out". Players can start any number of sequences, but they can have only one sequence of each color, so the maximum number of sequences is five. Any number can occur only once in a sequence and its mandatory to have one and only one "odd one out" card in the sequence.

The goal is to have the most points by the end of the game.