redirect.user.js

// ==UserScript==
// @name         New Userscript
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  try to take over the world!
// @author       You
// @include      http://tagpro-*.koalabeast.com:*
// @grant        none
// ==/UserScript==

tagpro.ready(function() {
    let whichServer = 'pi'; //case insensitive
    let thresholdPlayerCount = 4; //greater than or equal to
    let checkEvery = 5000; //5 seconds
    
    ////////////////////////
    
    let serverHost = "tagpro-"+whichServer.toLowerCase()+".koalabeast.com";
    if(serverHost===tagpro.serverHost) return console.warn('Already on '+whichServer.charAt(0).toUpperCase()+whichServer.slice(1));
    
    let gameCount = -1;
    let playerCount = -1;
    
    var socket = window.io.connect("ws://"+serverHost+":80", {transports: ["websocket"]});
    
    let interval = setInterval(function() {
        socket.emit('stats',{},function(data) { //data.games, data.players, data.playerCapacity
            if(data.players>=thresholdPlayerCount) {
                gameCount = data.games;
                playerCount = data.players;
                location.replace('http://'+serverHost+'/games/find');
            }
        });
    }, checkEvery);
    
    window.onbeforeunload = function(e) {
        if(tagpro.state===1)  {
            clearInterval(interval);
            socket.disconnect();
            return playerCount+" players in "+gameCount+" different games were found on "+whichServer.charAt(0).toUpperCase()+whichServer.slice(1)+". Leave to play a game on that server?"; //this won't show
        }
    };
});