$dbc = mysqli_connect(DB_HOST, DB_USER, DB_PASSWORD, DB_NAME);

if (mysqli_connect_errno()){
    trigger_error ('Could not connect to MySql: ' . mysqli_connect_error());
    echo "it had an error";
} else {
    mysqli_set_charset($dbc, 'utf8');
    echo "it connected";
}

function getGames($dbc){
    $query="SELECT * FROM games WHERE min_players <= ".$number." AND max_players >=".$number.";";
    $result = mysqli_query($dbc, $query) or trigger_error("Query: $query n<br />MySQL Error: " . mysqli_error($dbc));

    if(mysqli_affected_rows($dbc)) {
        return $result;
    } else {
        return "no affected rows";
    }
}

$result = getGames($dbc);
echo json_encode($result);

function getGames($dbc, $number) {
    // ...

echo $query;

$sql = sprintf('Your SELECT statement with %d number', $number);
echo $sql; // To visually verify the SQL is valid

$query = mysqli_query($dbc, $sql);

if (false !== $query) {
    return mysqli_num_rows($query);
} else {
    return mysqli_error($dbc);
}

if(mysqli_num_rows($result)) {
    return $result;
} else {
    return "no affected rows";
}