server.js

var express = require('express'),
    app = express(app),
    server = require('http').createServer(app);
// serve static files from the current directory
app.use(express.static(__dirname));
//we'll keep clients data here
var clients = {};
var updatedPowers = [];
var totalKills = [];
var allNames = [];
powerUpUpdate();

//get EurecaServer class
var EurecaServer = require('eureca.io').EurecaServer;
//create an instance of EurecaServer
var eurecaServer = new EurecaServer({
    allow: ['killPowerups', 'setInfo', 'spawnEnemy', 'kill', 'updateState', 'updatePowerUps',
        'nameChange', 'removePlayerHealth', 'displayScoreboard', 'printKillText'
    ]
});
//attach eureca.io to our http server
eurecaServer.attach(server);
//eureca.io provides events to detect clients connect/disconnect
//detect client connection
eurecaServer.onConnect(function(conn) {
    console.log('New Client id=%s ', conn.id, conn.remoteAddress);

    //the getClient method provide a proxy allowing us to call remote client functions
    var remote = eurecaServer.getClient(conn.id);

    //register the client
    clients[conn.id] = {
        id: conn.id,
        remote: remote
    };

    //here we call setId (defined in the client side)
    remote.setInfo({
        id: conn.id,
        powerups: updatedPowers
    });

});
//detect client disconnection
eurecaServer.onDisconnect(function(conn) {
    console.log('Client disconnected ', conn.id);
    var removeId = clients[conn.id].id;
    delete clients[conn.id];

    var index;
    allNames.forEach(function(each, i) {
        if (each.id === conn.id) {
            index = i
        }
    })
    allNames.splice(index, 1);

    for (var c in clients) {
        var remote = clients[c].remote;
        //here we call kill() method defined in the client side
        remote.kill(conn.id);
    }
});

eurecaServer.exports.handshake = function(connId) {
    var remote = clients[connId].remote;

    // loop thru all players
    for (var cc in clients) {

        if (cc === connId) {
            continue;
        }
        //send latest known position
        var x = clients[cc].laststate ? clients[cc].laststate.x : 0;
        var y = clients[cc].laststate ? clients[cc].laststate.y : 0;

        // send current player to new player
        remote.spawnEnemy(clients[cc].id, x, y);

        // send new player spawn to current player
        clients[cc].remote.spawnEnemy(connId, 0, 0);
    }
};

function powerUpUpdate() {
    var locs = [
        [2161, 2421],
        [2145, 1360],
        [1814, 1629],
        [1694, 1169],
        [670, 2043],
        [1022, 2421],
        [522, 1087],
        [324, 325],
        [889, 129],
        [1578, 200],
        [2261, 234],
        [1296, 815]
    ];
    var powerUpType = ['rifle', 'shotgun', 'health', 'shield', 'two-guns', 'rocket'];
    updatedPowers = [];
    for (var i = 0; i < 5; i++) {
        var pu = updatedPowers[i] = [
            locs.splice(Math.floor(locs.length * Math.random()), 1)[0],
            powerUpType[Math.floor(powerUpType.length * Math.random())]
        ];
    }

    for (var c in clients) {
        var remote = clients[c].remote;
        remote.updatePowerUps(updatedPowers);
    }
}

eurecaServer.exports.assignName = function(id, name) {
    allNames.push({
        id, name
    });
    for (var c in clients) {
        var remote = clients[c].remote;
        remote.nameChange(id, name, allNames);
    }
}


eurecaServer.exports.bulletHitsPlayer = function(playerShotandShooter) {
    for (var c in clients) {
        var remote = clients[c].remote;
        remote.removePlayerHealth(playerShotandShooter);
    }
}

eurecaServer.exports.pickupPowerUp = function() {
    for (var c in clients) {
        var remote = clients[c].remote;
        remote.killPowerups();
    }
    setTimeout(function() {
        powerUpUpdate();
    }, 3000);
};

eurecaServer.exports.killUpdate = function(packge) {
    totalKills.push(packge) //packge is the latest kill event
    var conn = this.connection;
    var updatedClient = clients[conn.id];

    for (var c in clients) {
        var remote = clients[c].remote;
        remote.printKillText(packge, allNames);
    }
}

eurecaServer.exports.scoreDisplay = function(id) { 
    if (totalKills.length === 0) return;
    var fullKDcount = []

    allNames.forEach(function(namePair) {
        var kdPair = []
        var player = namePair.name;
        var killCount = 0;
        var deathCount = 0;
        totalKills.forEach(function(killEvent) {

            if (namePair.id === killEvent.killer) {
                killCount += 1
            }
            if (namePair.id === killEvent.victim) {
                deathCount += 1
            }
        })
        kdPair[0] = player;
        kdPair[1] = killCount;
        kdPair[2] = deathCount;
        fullKDcount.push(kdPair);

    })

    var useableName;

    //we display to only the ID passed in the function to us
    for (var c in clients) {
        var remote = clients[c].remote;
        remote.displayScoreboard(fullKDcount, id);
    }
}


eurecaServer.exports.handleKeys = function(keys) {
    var conn = this.connection;
    var updatedClient = clients[conn.id];

    for (var c in clients) {
        var remote = clients[c].remote;

        remote.updateState(updatedClient.id, keys);

        //keep last known state so we can send it to new connected clients
        clients[c].laststate = keys;
    }
};
server.listen(process.env.PORT);