function form () {

    function sub01 () {

        if (isset($_GET["form"])) {
            switch ($_GET["form"]) {
                case '1':
                    $_SESSION["players_count"] = [
                        "count" => (int) $_GET["count"],
                    ];
                    $_SESSION["form"] = 2;
                    break;

                case '2':
                    $_SESSION["players"] = [];
                    $i = 1;
                    while (true) {
                        if (array_key_exists("name_player_$i", $_GET)) {
                            $_SESSION["players"][] = [$_GET["name_player_$i"], $_GET["type_player_$i"]];
                        } else {
                            break;
                        }
                        $i++;
                    }

                    $_SESSION["form"] = 3;
                    break;
            }
        }
    }

    sub();

    function sub02() {
        $index = $_SESSION["form"];
        $form = '
                    <form method="GET">
                        <fieldset>
                            <legend>Enter data players</legend>
                            <label>%s</label>
                            %s
                            <input type="hidden" name="form" value="%s">
                        </fieldset>
                    </form>
                ';
        switch ($index) {
            case 3:
                $field = "";
                if (isset($_SESSION["players"])) {
                    $i = 1;
                    foreach ($_SESSION["players"] as $key => $value) {
                        $field .= "😆 $i. " . "Player [" . $value[0] . "] : ready => OK!" . '<br>';
                        $i++;
                    }
                }
                $field .= '<a href="game"><button>Start Game</button></a>';
                return $field;
                break;
            case 2:
                $count_players = $_SESSION["players_count"]["count"];
                $name = "Enter player names" . "<br>";
                $field = '';
                for ($i = 0; $i < $count_players; $i++) {
                    $field .= $i + 1 . '. <input placeholder="name player" required type="text" name="name_player_'. ($i + 1) . '">';
                    $field .=
                    '
                    <select name="type_player_' . ($i + 1) .'">
                        <option value="Human">Human</option>
                        <option value="Machine">Machine</option>
                    </select> <br>
                    ';

                };
                $field .= '<input type="submit" name="btn" value="Send">';
                $code_form =  "2";
                return sprintf($form, $name, $field , $code_form);

            case 1:
                $name = "Number of players? => ";
                $field = '<input required type="number" name="count">';
                $field .= '<input type="submit" name="btn" value="Send">';
                $code_form =  "1";
                return sprintf($form, $name, $field , $code_form);
        }
    }

    sub02();
}