There are two players, and each one gets 4 cards, a "4", a "3", a "2", a "1". Then the players reveal one of the cards in their hand simultaneously in rounds. If both cards are identical, or if one is "1" and the other "4", both cards are thrown away. Otherwise the player who played the higher card takes it back to his or her hand, whereas the lower card is thrown away. The player who is unable to put down a card loses.
You play against the computer by clicking on the cards in your hand.
Erich Prisner, 2012