sublime,
<script>
var user = {};
var game = [1, 2, 3, 4, 5, 6];
user.last_game = [];
for (let i = 0; i < 3; i++) {
let RandomInt = game.length * Math.random() | 0;
user.last_game.push(game.splice(RandomInt, 1)[0]);
}
document.write(JSON.stringify(user.last_game, "", 4))
</script>