This card game combines strategy, to choose the cards to keep, those to discard and to decide the right moment of ending the game ,according to his cards and those estimated of its opponents. It is ale benefitial for the memory, to remember the cards seen, their location, to check if the opponents have discarded them or not, etc.

In this game, the player plays against the system (from 2 to 4 players, so 1 to 3 system players). It is also possible to set the game level of the system (applicable to all system players) and the time to think for each system player (and therefore the time for the player to discard cards).

The rules of the game are as follows:
The goal of 4 is to get the lowest score at the end of the game. Each card has a value (Red Kings=0; As=1; 2=2; 3=3; ...; J=11; Q=12; Black Kings=13) and the total is the player's score.
At the start of a game, each player looks 2 of his 4 cards.
During the game, if a player drops a Queen, he can look at one of his cards. If he drops a Jack, he can look at a card from his opponents.
During the game, the player can take one card from the stack, watch it, and change it with one of his cards if he is interested or deposit it on the discard pile if not. He may also, instead, take the first card from the discard pile if he is interested and deposit one of his cards.
At any time, the player may discard a card with the same value as the first card in the discard pile. In case of error, he draws a card, puts it in his pile, without looking at it.
When a player thinks he can win, he presses "Stop". This is the last round and the opponents play their last card.
At the end of the game, the score of each player is displayed and the winner is the one with the minimum score.