var timeleft = 6;
var gameTimer = setInterval(function(){
    timeleft--;
    afficherChaine("Le jeu va commencer dans " + timeleft + " secondes !"); //Just prints something at the screen for the user
    console.log("First");
    if(timeleft <= 0){
        clearInterval(gameTimer);
        console.log("Second");
        jouer();
    }
},1000);

First
Second

First
Second
First
Second
First
Second
First
Second
...