PHP MasterMind

<?php
    function write(string $message)
    {
        fwrite(STDOUT, $message . PHP_EOL);
    }

    $n1 = random_int(0, 9);
    $n2 = random_int(0, 9);
    $n3 = random_int(0, 9);
    $n4 = random_int(0, 9);
    $mysteryArray = [$n1, $n2, $n3, $n4];
    $mystery = implode($mysteryArray);
    $guess = null;
    $tries = 0;

    write("MASTERMIND");

    // While guess is wrong and number of tries not reached
    while ($guess != $mystery && $tries < 10) {
        // Prompt to User his guess
        if ($tries > 0) {
            write("You guessed: $guess");
        }

        // Read user input
        write("Please guess a 4 digit number: ");
        $input = fopen("php://stdin", "r");
        $guess = fgets($input);
        $guess = trim($guess);
        $guess = str_replace(" ", "", $guess);

        // CHEAT
        if ($guess === "CHEAT") {
            write("GG YOU WON!   ...cheater...");
            write("The mystery number was $mystery!");
            exit();
        }

        // Validate user input
        if (!is_numeric($guess)) {
            write("You need to enter numbers...");
            continue;
        }
        if (strlen($guess) !== 4) {
            write("You need to enter 4 numbers...");
            continue;
        }

        // Incrementing tries
        ++$tries;

        // Clues for user
        write("Sorry that is not the mystery number");
        $guessArray = str_split($guess);
        foreach ($guessArray as $index => $proposal) {
            if ($mysteryArray[$index] == $proposal) {
                write("{$proposal} is in the right spot!");
            } elseif (in_array($proposal, $mysteryArray)) {
                write("{$proposal} is in the number");
            }
        }
    }

    if ($tries === 10) {
        write("$tries tries reached, sorry you loose! :(");
        write("The mystery number was $mystery");
        exit();
    }

    write("OMG, GG you guessed it! :D");