Based on the popular "spot the differences" challenges found in books, newspapers and elsewhere, Difference challenges your abilities to observe and react quickly. The deck includes two sets of double-sided cards, with one set being more challenging than the other. Place one card in the center of the table, then deal the rest out to players as evenly as possible.

To start, each player looks at the top card of her stack, then tries to spot the two differences between her card in hand and the reference card on the table. Whoever spots her particular differences first stops play, demonstrates them to everyone, places her card on top of the reference card (creating a new challenge for everyone), then draws the next card from her deck. Whoever gets rid of all of her cards first wins!