13. PLUS - Bonus 1 - An ONLINE lobby

NOTE: Version 1.2.0 introduced LAN lobbys. This chapter only covers the online lobby

The update to version 1.0 introduces a new lobby system for online servers.

That means you can now add an online lobby to your game.

This part of the tutorial will explain everything you'll need to know. Before we start, please create a new project and load the sample project (add all files from the GMnet ENGINE asset).

We now have everything we created in this tutorial and more. The lobby is one of these things. Let me take you on a tour on how it works.

GMnet PUNCH needs to be activated. Please follow chapter 2 and 3 for this.

Testing the lobby

When you press L when starting the game you will be brought to the demo lobby room. This is a very simple demo room that can only show four servers. Once we are done, you'll be able to create an even better lobby.

To test it, see if a server is online and connect to it via the lobby. Please note that you have to set up a master server before, as explained in chapter 3. If you use the demo master server, please note that there might be "GMnet PUNCH Demo Servers" in the server list. You can not join them, they were created using the UDPHP demo project. Both use the same lobby and the same demo master server.

You can also create a server and fire up a second game and see if you can join it.

The new concepts: Gamenames

In htme_init there is a new variable you need to change when creating your own game (keep the default for the demo project though, otherwise you can't join demo servers via the lobby):

 *  Shortname of this game
 *  + version
 *  Example: htme_demo100
self.gamename = "htme_demo100"

This string represents your game and the version of your game. If you update your game and it's server is not compatible with older versions, change this string and you can prevent players from joining older servers in the lobby (Please note that this is only for the lobby, if your players are able to connect manually, you need to implement your own way of kicking him out of the game again after he has connected, see How can my clients get the gamename and data strings after they connected? below for more info)

You can change it at any time, for example if you have multiple gamemodes you want to mark in the lobby via htme_setGamename(name) and get it via htme_getGamename().

Data strings

Asside from the gamename string, there are 7 more strings that can be used to identify your game in the lobby.

Start the demo game and create a server. You will be asked to enter the name of the server and a description. These are data strings 2 and 3. The demo lobby uses them for these purposes, but when making your own game, you can use them however you want. 4-8 are unused by the demo project.

Let's open the N-key event of htme_obj_menu (this event creates the server).

You'll find this part after the server has successfully been created:

htme_setData(2,get_string("How should this server be called (for the lobby)?","GMnet ENGINE Demo Server"));
htme_setData(3,get_string("Enter a server description (for the lobby)?","A server created for the GMnet ENGINE demo project"));

As you can see, we set the server name and description right after the server was started using htme_setData(n,string). We use 2 for server name and 3 for description. You can also on the server end retrieve these strings using htme_getData(n).

If you want to update any data string later, after the server connected to the master server, you need to use htme_commitData(). This syncs all data strings to the master server. You MUST NOT use it here, because the server hasn't connected to the master server yet!

A note for GMnet PUNCH users: The gamename is data string 1.

Building the lobby

Ah, the lobby. Finally we are ready to build it.

The room of the lobby is the room udphhtme_lobby. This room only contains the object obj_udphphtme_lobby. This object controls the lobby. Let's dive into it!

The create event

//IF YOU USE GMnet PUNCH - it will only let you connect to GMnet PUNCH servers:
if (!script_exists(asset_get_index("htme_init"))) { = "udphp_demo120"
//IF YOU USE GMnet ENGINE - it will only let you conect to GMnet ENGINE servers
else { = "htme_demo121"

///Recieve lobby data from the master server

First the variable game gets set. We use this to prevent GMnet ENGINE players from joining GMnet PUNCH servers and vice-versa. As said before, this object is used in GMnet ENGINE demo project and GMnet PUNCH standalone demo project, this is why it has seperate code for both.

The important part here is [udphp_downloadServerList](functions/udphp_downloadServerList). This will tell GMnet PUNCH (the part of the engine that controls communication with the master server) to download a list of servers from the master server. The paramters allow for filtering and sorting the result, we use this to only get results that match our game name. More information about what you can filter, can be found on the usage page of udphp_downloadServerList.

You use your own filtering variables later when creating your lobby.

The networking event

///Waits for master server response

This code checks if the master server sent the server list and updates it. This is not included in htme_networking(); and therefor has to be run here.

The draw event

The draw event is split up into different sub-scripts:

'Background', 'Title and Controls', 'Online servers'

Draws some background colors and some text, not important

'Servers (Loop)'

This draws the actual server list.

Let's analyze it:

///Servers (Loop)
var l = global.udphp_downloadlist;
for (var i = 0; i<4;i++) {

First, the list global.udphp_downloadlist is stored in the local variable l (because it's shorter). This ds_list contains all the servers we got from the master server.

Then it begins a loop that loops through the first 4 servers in the list we got by the master server, everything is in this loop and then it draws a nice little number for each server.

    if (ds_exists(l,ds_type_list)) {
        if (ds_list_size(l)>i) {

Now, this is the interesting part.

First we check if the downloadlist was already created (it get's created once the list has been downloaded). After that we check if it has at least as many entrys as the server we want to list. For this example we assume i is 1. That means it checks if there is atleast one server in the list. If yes, we have an entry we can now draw.

            //Get stuff from the downloadlist
            var entry = l[| i];
            var ip = entry[? "ip"];
            var game = entry[? "data1"];
            var servername = entry[? "data2"];
            var description = entry[? "data3"];

Now the entry (a ds_map) for our server is extracted from the list and we get the gamename, which is stored in data1, the ip, which is stored in the key "ip", the name of the server, which we stored in data2, and so on.

            draw_text(70,85+80*i,servername+" | "+ip);

Now we just draw everything.


Again, just some text, not important.

The press 1-4 key events

Pressing 1-4 on the keyboard will connect to that game. Let's see how!

var l = global.udphp_downloadlist;
if (ds_exists(l,ds_type_list)) {
    if (ds_list_size(l)>0) {
        var entry = l[| 0];
        var ip = entry[? "ip"];
        var game = entry[? "data1"];

We again open the downloadlist and check if server 1 is in it, if yes we continue.

        if (game != {
           //Not compatible game, exit
           show_message("Game server or version is incompatible!");

Remember the filtering variable we created in the create-event? We use it here to check if the server is a GMnet ENGINE demo game. If not we cancel. Please note, that this is propably not needed here, since we filtered out all, but our game in the create event, when we ran udphp_downloadServerList.

        //====GMnet PUNCH DEMO ONLY
        if (!script_exists(asset_get_index("htme_init"))) {
           //This code is irrelevant for GMnet ENGINE and has been removed
        //====GMnet ENGINE DEMO ONLY
        else {
            //Setup client, on success go to waiting room, otherwise end game
            //We don't actually know the port, but that doesn't matter, the master
            //server will tell us the port when we connect
            //THE LINE BELOW is equivalent to:
            //if (htme_clientStart(ip, 0)) {
            if (script_execute(asset_get_index("htme_clientStart"),ip, 0)) {
                //Wait for connection success!
            } else {
                show_message("Could not start client! Check your network configuration!");
    } else {
      //Do nothing - There is no server on this slot
} else {
  //Do nothing - There is no server on this slot

This is the rest of the script. We once again check if we are running the GMnet ENGINE demo project and then we begin connection.

We call htme_clientStart with the ip we got from the list and leave the port at 0. Why? Because we don't know the port. But that doesn't matter, because when connecting to the server, GMnet ENGINE will automatically resolve the port using UDPHP.

Afer that we just go to the waiting room. Done! The rest is the default client connection you know and love.

And this is how you create a lobby! Now go ahead and do it! :)

How can my clients get the gamename and data strings after they connected?

Now, you might want to get the datastrings and the gamename after you connected. For example to display the name of the server in a corner, or to make sure the server is comaptible to the client when connecting manually.

For this you just create a object like the time syncing object. You sync it with the engine, so all other players get it and sync 8 variables that contain the value of the gamename string and the 7 data strings.

If you need help with that, contact me :)

Anything missing?

If this bonus chapter lacks something important, please let me know. If you have any problems feel free to contact me. I know this is quite complicated compared to the rest, so don't be frustrated when you have problems.

» Next topic: Bonus 2 - Global Sync (Sync a pool of variables editable by all)

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